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postgres/src/backend/optimizer/prep/prepunion.c
Tom Lane c4c2885cbb Fix UNION/INTERSECT/EXCEPT over no columns. 
Since 9.4, we've allowed the syntax "select union select" and variants
of that.  However, the planner wasn't expecting a no-column set operation
and ended up treating the set operation as if it were UNION ALL.

Turns out it's trivial to fix in v10 and later; we just need to be careful
about not generating a Sort node with no sort keys.  However, since a weird
corner case like this is never going to be exercised by developers, we'd
better have thorough regression tests if we want to consider it supported.

Per report from Victor Yegorov.

Discussion: https://postgr.es/m/CAGnEbojGJrRSOgJwNGM7JSJZpVAf8xXcVPbVrGdhbVEHZ-BUMw@mail.gmail.com
2017-12-22 12:08:06 -05:00

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/*-------------------------------------------------------------------------
*
* prepunion.c
* Routines to plan set-operation queries. The filename is a leftover
* from a time when only UNIONs were implemented.
*
* There are two code paths in the planner for set-operation queries.
* If a subquery consists entirely of simple UNION ALL operations, it
* is converted into an "append relation". Otherwise, it is handled
* by the general code in this module (plan_set_operations and its
* subroutines). There is some support code here for the append-relation
* case, but most of the heavy lifting for that is done elsewhere,
* notably in prepjointree.c and allpaths.c.
*
* There is also some code here to support planning of queries that use
* inheritance (SELECT FROM foo*). Inheritance trees are converted into
* append relations, and thenceforth share code with the UNION ALL case.
*
*
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/prep/prepunion.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <limits.h>
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "catalog/partition.h"
#include "catalog/pg_inherits_fn.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/cost.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "optimizer/prep.h"
#include "optimizer/tlist.h"
#include "parser/parse_coerce.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/selfuncs.h"
typedef struct
{
PlannerInfo *root;
int nappinfos;
AppendRelInfo **appinfos;
} adjust_appendrel_attrs_context;
static Path *recurse_set_operations(Node *setOp, PlannerInfo *root,
List *colTypes, List *colCollations,
bool junkOK,
int flag, List *refnames_tlist,
List **pTargetList,
double *pNumGroups);
static Path *generate_recursion_path(SetOperationStmt *setOp,
PlannerInfo *root,
List *refnames_tlist,
List **pTargetList);
static Path *generate_union_path(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList,
double *pNumGroups);
static Path *generate_nonunion_path(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList,
double *pNumGroups);
static List *recurse_union_children(Node *setOp, PlannerInfo *root,
SetOperationStmt *top_union,
List *refnames_tlist,
List **tlist_list);
static Path *make_union_unique(SetOperationStmt *op, Path *path, List *tlist,
PlannerInfo *root);
static bool choose_hashed_setop(PlannerInfo *root, List *groupClauses,
Path *input_path,
double dNumGroups, double dNumOutputRows,
const char *construct);
static List *generate_setop_tlist(List *colTypes, List *colCollations,
int flag,
Index varno,
bool hack_constants,
List *input_tlist,
List *refnames_tlist);
static List *generate_append_tlist(List *colTypes, List *colCollations,
bool flag,
List *input_tlists,
List *refnames_tlist);
static List *generate_setop_grouplist(SetOperationStmt *op, List *targetlist);
static void expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte,
Index rti);
static void expand_partitioned_rtentry(PlannerInfo *root,
RangeTblEntry *parentrte,
Index parentRTindex, Relation parentrel,
PlanRowMark *top_parentrc, LOCKMODE lockmode,
List **appinfos, List **partitioned_child_rels);
static void expand_single_inheritance_child(PlannerInfo *root,
RangeTblEntry *parentrte,
Index parentRTindex, Relation parentrel,
PlanRowMark *top_parentrc, Relation childrel,
List **appinfos, RangeTblEntry **childrte_p,
Index *childRTindex_p);
static void make_inh_translation_list(Relation oldrelation,
Relation newrelation,
Index newvarno,
List **translated_vars);
static Bitmapset *translate_col_privs(const Bitmapset *parent_privs,
List *translated_vars);
static Node *adjust_appendrel_attrs_mutator(Node *node,
adjust_appendrel_attrs_context *context);
static Relids adjust_child_relids(Relids relids, int nappinfos,
AppendRelInfo **appinfos);
static List *adjust_inherited_tlist(List *tlist,
AppendRelInfo *context);
/*
* plan_set_operations
*
* Plans the queries for a tree of set operations (UNION/INTERSECT/EXCEPT)
*
* This routine only deals with the setOperations tree of the given query.
* Any top-level ORDER BY requested in root->parse->sortClause will be handled
* when we return to grouping_planner; likewise for LIMIT.
*
* What we return is an "upperrel" RelOptInfo containing at least one Path
* that implements the set-operation tree. In addition, root->processed_tlist
* receives a targetlist representing the output of the topmost setop node.
*/
RelOptInfo *
plan_set_operations(PlannerInfo *root)
{
Query *parse = root->parse;
SetOperationStmt *topop = castNode(SetOperationStmt, parse->setOperations);
Node *node;
RangeTblEntry *leftmostRTE;
Query *leftmostQuery;
RelOptInfo *setop_rel;
Path *path;
List *top_tlist;
Assert(topop);
/* check for unsupported stuff */
Assert(parse->jointree->fromlist == NIL);
Assert(parse->jointree->quals == NULL);
Assert(parse->groupClause == NIL);
Assert(parse->havingQual == NULL);
Assert(parse->windowClause == NIL);
Assert(parse->distinctClause == NIL);
/*
* We'll need to build RelOptInfos for each of the leaf subqueries, which
* are RTE_SUBQUERY rangetable entries in this Query. Prepare the index
* arrays for that.
*/
setup_simple_rel_arrays(root);
/*
* Find the leftmost component Query. We need to use its column names for
* all generated tlists (else SELECT INTO won't work right).
*/
node = topop->larg;
while (node && IsA(node, SetOperationStmt))
node = ((SetOperationStmt *) node)->larg;
Assert(node && IsA(node, RangeTblRef));
leftmostRTE = root->simple_rte_array[((RangeTblRef *) node)->rtindex];
leftmostQuery = leftmostRTE->subquery;
Assert(leftmostQuery != NULL);
/*
* We return our results in the (SETOP, NULL) upperrel. For the moment,
* this is also the parent rel of all Paths in the setop tree; we may well
* change that in future.
*/
setop_rel = fetch_upper_rel(root, UPPERREL_SETOP, NULL);
/*
* We don't currently worry about setting setop_rel's consider_parallel
* flag, nor about allowing FDWs to contribute paths to it.
*/
/*
* If the topmost node is a recursive union, it needs special processing.
*/
if (root->hasRecursion)
{
path = generate_recursion_path(topop, root,
leftmostQuery->targetList,
&top_tlist);
}
else
{
/*
* Recurse on setOperations tree to generate paths for set ops. The
* final output path should have just the column types shown as the
* output from the top-level node, plus possibly resjunk working
* columns (we can rely on upper-level nodes to deal with that).
*/
path = recurse_set_operations((Node *) topop, root,
topop->colTypes, topop->colCollations,
true, -1,
leftmostQuery->targetList,
&top_tlist,
NULL);
}
/* Must return the built tlist into root->processed_tlist. */
root->processed_tlist = top_tlist;
/* Add only the final path to the SETOP upperrel. */
add_path(setop_rel, path);
/* Let extensions possibly add some more paths */
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_SETOP,
NULL, setop_rel);
/* Select cheapest path */
set_cheapest(setop_rel);
return setop_rel;
}
/*
* recurse_set_operations
* Recursively handle one step in a tree of set operations
*
* colTypes: OID list of set-op's result column datatypes
* colCollations: OID list of set-op's result column collations
* junkOK: if true, child resjunk columns may be left in the result
* flag: if >= 0, add a resjunk output column indicating value of flag
* refnames_tlist: targetlist to take column names from
*
* Returns a path for the subtree, as well as these output parameters:
* *pTargetList: receives the fully-fledged tlist for the subtree's top plan
* *pNumGroups: if not NULL, we estimate the number of distinct groups
* in the result, and store it there
*
* The pTargetList output parameter is mostly redundant with the pathtarget
* of the returned path, but for the moment we need it because much of the
* logic in this file depends on flag columns being marked resjunk. Pending
* a redesign of how that works, this is the easy way out.
*
* We don't have to care about typmods here: the only allowed difference
* between set-op input and output typmods is input is a specific typmod
* and output is -1, and that does not require a coercion.
*/
static Path *
recurse_set_operations(Node *setOp, PlannerInfo *root,
List *colTypes, List *colCollations,
bool junkOK,
int flag, List *refnames_tlist,
List **pTargetList,
double *pNumGroups)
{
if (IsA(setOp, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) setOp;
RangeTblEntry *rte = root->simple_rte_array[rtr->rtindex];
Query *subquery = rte->subquery;
RelOptInfo *rel;
PlannerInfo *subroot;
RelOptInfo *final_rel;
Path *subpath;
Path *path;
List *tlist;
Assert(subquery != NULL);
/*
* We need to build a RelOptInfo for each leaf subquery. This isn't
* used for much here, but it carries the subroot data structures
* forward to setrefs.c processing.
*/
rel = build_simple_rel(root, rtr->rtindex, NULL);
/* plan_params should not be in use in current query level */
Assert(root->plan_params == NIL);
/* Generate a subroot and Paths for the subquery */
subroot = rel->subroot = subquery_planner(root->glob, subquery,
root,
false,
root->tuple_fraction);
/*
* It should not be possible for the primitive query to contain any
* cross-references to other primitive queries in the setop tree.
*/
if (root->plan_params)
elog(ERROR, "unexpected outer reference in set operation subquery");
/*
* Mark rel with estimated output rows, width, etc. Note that we have
* to do this before generating outer-query paths, else
* cost_subqueryscan is not happy.
*/
set_subquery_size_estimates(root, rel);
/*
* For the moment, we consider only a single Path for the subquery.
* This should change soon (make it look more like
* set_subquery_pathlist).
*/
final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
subpath = get_cheapest_fractional_path(final_rel,
root->tuple_fraction);
/*
* Stick a SubqueryScanPath atop that.
*
* We don't bother to determine the subquery's output ordering since
* it won't be reflected in the set-op result anyhow; so just label
* the SubqueryScanPath with nil pathkeys. (XXX that should change
* soon too, likely.)
*/
path = (Path *) create_subqueryscan_path(root, rel, subpath,
NIL, NULL);
/*
* Figure out the appropriate target list, and update the
* SubqueryScanPath with the PathTarget form of that.
*/
tlist = generate_setop_tlist(colTypes, colCollations,
flag,
rtr->rtindex,
true,
subroot->processed_tlist,
refnames_tlist);
path = apply_projection_to_path(root, rel, path,
create_pathtarget(root, tlist));
/* Return the fully-fledged tlist to caller, too */
*pTargetList = tlist;
/*
* Estimate number of groups if caller wants it. If the subquery used
* grouping or aggregation, its output is probably mostly unique
* anyway; otherwise do statistical estimation.
*
* XXX you don't really want to know about this: we do the estimation
* using the subquery's original targetlist expressions, not the
* subroot->processed_tlist which might seem more appropriate. The
* reason is that if the subquery is itself a setop, it may return a
* processed_tlist containing "varno 0" Vars generated by
* generate_append_tlist, and those would confuse estimate_num_groups
* mightily. We ought to get rid of the "varno 0" hack, but that
* requires a redesign of the parsetree representation of setops, so
* that there can be an RTE corresponding to each setop's output.
*/
if (pNumGroups)
{
if (subquery->groupClause || subquery->groupingSets ||
subquery->distinctClause ||
subroot->hasHavingQual || subquery->hasAggs)
*pNumGroups = subpath->rows;
else
*pNumGroups = estimate_num_groups(subroot,
get_tlist_exprs(subquery->targetList, false),
subpath->rows,
NULL);
}
return (Path *) path;
}
else if (IsA(setOp, SetOperationStmt))
{
SetOperationStmt *op = (SetOperationStmt *) setOp;
Path *path;
/* UNIONs are much different from INTERSECT/EXCEPT */
if (op->op == SETOP_UNION)
path = generate_union_path(op, root,
refnames_tlist,
pTargetList,
pNumGroups);
else
path = generate_nonunion_path(op, root,
refnames_tlist,
pTargetList,
pNumGroups);
/*
* If necessary, add a Result node to project the caller-requested
* output columns.
*
* XXX you don't really want to know about this: setrefs.c will apply
* fix_upper_expr() to the Result node's tlist. This would fail if the
* Vars generated by generate_setop_tlist() were not exactly equal()
* to the corresponding tlist entries of the subplan. However, since
* the subplan was generated by generate_union_plan() or
* generate_nonunion_plan(), and hence its tlist was generated by
* generate_append_tlist(), this will work. We just tell
* generate_setop_tlist() to use varno 0.
*/
if (flag >= 0 ||
!tlist_same_datatypes(*pTargetList, colTypes, junkOK) ||
!tlist_same_collations(*pTargetList, colCollations, junkOK))
{
*pTargetList = generate_setop_tlist(colTypes, colCollations,
flag,
0,
false,
*pTargetList,
refnames_tlist);
path = apply_projection_to_path(root,
path->parent,
path,
create_pathtarget(root,
*pTargetList));
}
return path;
}
else
{
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(setOp));
*pTargetList = NIL;
return NULL; /* keep compiler quiet */
}
}
/*
* Generate path for a recursive UNION node
*/
static Path *
generate_recursion_path(SetOperationStmt *setOp, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList)
{
RelOptInfo *result_rel = fetch_upper_rel(root, UPPERREL_SETOP, NULL);
Path *path;
Path *lpath;
Path *rpath;
List *lpath_tlist;
List *rpath_tlist;
List *tlist;
List *groupList;
double dNumGroups;
/* Parser should have rejected other cases */
if (setOp->op != SETOP_UNION)
elog(ERROR, "only UNION queries can be recursive");
/* Worktable ID should be assigned */
Assert(root->wt_param_id >= 0);
/*
* Unlike a regular UNION node, process the left and right inputs
* separately without any intention of combining them into one Append.
*/
lpath = recurse_set_operations(setOp->larg, root,
setOp->colTypes, setOp->colCollations,
false, -1,
refnames_tlist,
&lpath_tlist,
NULL);
/* The right path will want to look at the left one ... */
root->non_recursive_path = lpath;
rpath = recurse_set_operations(setOp->rarg, root,
setOp->colTypes, setOp->colCollations,
false, -1,
refnames_tlist,
&rpath_tlist,
NULL);
root->non_recursive_path = NULL;
/*
* Generate tlist for RecursiveUnion path node --- same as in Append cases
*/
tlist = generate_append_tlist(setOp->colTypes, setOp->colCollations, false,
list_make2(lpath_tlist, rpath_tlist),
refnames_tlist);
*pTargetList = tlist;
/*
* If UNION, identify the grouping operators
*/
if (setOp->all)
{
groupList = NIL;
dNumGroups = 0;
}
else
{
/* Identify the grouping semantics */
groupList = generate_setop_grouplist(setOp, tlist);
/* We only support hashing here */
if (!grouping_is_hashable(groupList))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement recursive UNION"),
errdetail("All column datatypes must be hashable.")));
/*
* For the moment, take the number of distinct groups as equal to the
* total input size, ie, the worst case.
*/
dNumGroups = lpath->rows + rpath->rows * 10;
}
/*
* And make the path node.
*/
path = (Path *) create_recursiveunion_path(root,
result_rel,
lpath,
rpath,
create_pathtarget(root, tlist),
groupList,
root->wt_param_id,
dNumGroups);
return path;
}
/*
* Generate path for a UNION or UNION ALL node
*/
static Path *
generate_union_path(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList,
double *pNumGroups)
{
RelOptInfo *result_rel = fetch_upper_rel(root, UPPERREL_SETOP, NULL);
double save_fraction = root->tuple_fraction;
List *pathlist;
List *child_tlists1;
List *child_tlists2;
List *tlist_list;
List *tlist;
Path *path;
/*
* If plain UNION, tell children to fetch all tuples.
*
* Note: in UNION ALL, we pass the top-level tuple_fraction unmodified to
* each arm of the UNION ALL. One could make a case for reducing the
* tuple fraction for later arms (discounting by the expected size of the
* earlier arms' results) but it seems not worth the trouble. The normal
* case where tuple_fraction isn't already zero is a LIMIT at top level,
* and passing it down as-is is usually enough to get the desired result
* of preferring fast-start plans.
*/
if (!op->all)
root->tuple_fraction = 0.0;
/*
* If any of my children are identical UNION nodes (same op, all-flag, and
* colTypes) then they can be merged into this node so that we generate
* only one Append and unique-ification for the lot. Recurse to find such
* nodes and compute their children's paths.
*/
pathlist = list_concat(recurse_union_children(op->larg, root,
op, refnames_tlist,
&child_tlists1),
recurse_union_children(op->rarg, root,
op, refnames_tlist,
&child_tlists2));
tlist_list = list_concat(child_tlists1, child_tlists2);
/*
* Generate tlist for Append plan node.
*
* The tlist for an Append plan isn't important as far as the Append is
* concerned, but we must make it look real anyway for the benefit of the
* next plan level up.
*/
tlist = generate_append_tlist(op->colTypes, op->colCollations, false,
tlist_list, refnames_tlist);
*pTargetList = tlist;
/*
* Append the child results together.
*/
path = (Path *) create_append_path(result_rel, pathlist, NIL,
NULL, 0, false, NIL, -1);
/* We have to manually jam the right tlist into the path; ick */
path->pathtarget = create_pathtarget(root, tlist);
/*
* For UNION ALL, we just need the Append path. For UNION, need to add
* node(s) to remove duplicates.
*/
if (!op->all)
path = make_union_unique(op, path, tlist, root);
/*
* Estimate number of groups if caller wants it. For now we just assume
* the output is unique --- this is certainly true for the UNION case, and
* we want worst-case estimates anyway.
*/
if (pNumGroups)
*pNumGroups = path->rows;
/* Undo effects of possibly forcing tuple_fraction to 0 */
root->tuple_fraction = save_fraction;
return path;
}
/*
* Generate path for an INTERSECT, INTERSECT ALL, EXCEPT, or EXCEPT ALL node
*/
static Path *
generate_nonunion_path(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList,
double *pNumGroups)
{
RelOptInfo *result_rel = fetch_upper_rel(root, UPPERREL_SETOP, NULL);
double save_fraction = root->tuple_fraction;
Path *lpath,
*rpath,
*path;
List *lpath_tlist,
*rpath_tlist,
*tlist_list,
*tlist,
*groupList,
*pathlist;
double dLeftGroups,
dRightGroups,
dNumGroups,
dNumOutputRows;
bool use_hash;
SetOpCmd cmd;
int firstFlag;
/*
* Tell children to fetch all tuples.
*/
root->tuple_fraction = 0.0;
/* Recurse on children, ensuring their outputs are marked */
lpath = recurse_set_operations(op->larg, root,
op->colTypes, op->colCollations,
false, 0,
refnames_tlist,
&lpath_tlist,
&dLeftGroups);
rpath = recurse_set_operations(op->rarg, root,
op->colTypes, op->colCollations,
false, 1,
refnames_tlist,
&rpath_tlist,
&dRightGroups);
/* Undo effects of forcing tuple_fraction to 0 */
root->tuple_fraction = save_fraction;
/*
* For EXCEPT, we must put the left input first. For INTERSECT, either
* order should give the same results, and we prefer to put the smaller
* input first in order to minimize the size of the hash table in the
* hashing case. "Smaller" means the one with the fewer groups.
*/
if (op->op == SETOP_EXCEPT || dLeftGroups <= dRightGroups)
{
pathlist = list_make2(lpath, rpath);
tlist_list = list_make2(lpath_tlist, rpath_tlist);
firstFlag = 0;
}
else
{
pathlist = list_make2(rpath, lpath);
tlist_list = list_make2(rpath_tlist, lpath_tlist);
firstFlag = 1;
}
/*
* Generate tlist for Append plan node.
*
* The tlist for an Append plan isn't important as far as the Append is
* concerned, but we must make it look real anyway for the benefit of the
* next plan level up. In fact, it has to be real enough that the flag
* column is shown as a variable not a constant, else setrefs.c will get
* confused.
*/
tlist = generate_append_tlist(op->colTypes, op->colCollations, true,
tlist_list, refnames_tlist);
*pTargetList = tlist;
/*
* Append the child results together.
*/
path = (Path *) create_append_path(result_rel, pathlist, NIL,
NULL, 0, false, NIL, -1);
/* We have to manually jam the right tlist into the path; ick */
path->pathtarget = create_pathtarget(root, tlist);
/* Identify the grouping semantics */
groupList = generate_setop_grouplist(op, tlist);
/*
* Estimate number of distinct groups that we'll need hashtable entries
* for; this is the size of the left-hand input for EXCEPT, or the smaller
* input for INTERSECT. Also estimate the number of eventual output rows.
* In non-ALL cases, we estimate each group produces one output row; in
* ALL cases use the relevant relation size. These are worst-case
* estimates, of course, but we need to be conservative.
*/
if (op->op == SETOP_EXCEPT)
{
dNumGroups = dLeftGroups;
dNumOutputRows = op->all ? lpath->rows : dNumGroups;
}
else
{
dNumGroups = Min(dLeftGroups, dRightGroups);
dNumOutputRows = op->all ? Min(lpath->rows, rpath->rows) : dNumGroups;
}
/*
* Decide whether to hash or sort, and add a sort node if needed.
*/
use_hash = choose_hashed_setop(root, groupList, path,
dNumGroups, dNumOutputRows,
(op->op == SETOP_INTERSECT) ? "INTERSECT" : "EXCEPT");
if (groupList && !use_hash)
path = (Path *) create_sort_path(root,
result_rel,
path,
make_pathkeys_for_sortclauses(root,
groupList,
tlist),
-1.0);
/*
* Finally, add a SetOp path node to generate the correct output.
*/
switch (op->op)
{
case SETOP_INTERSECT:
cmd = op->all ? SETOPCMD_INTERSECT_ALL : SETOPCMD_INTERSECT;
break;
case SETOP_EXCEPT:
cmd = op->all ? SETOPCMD_EXCEPT_ALL : SETOPCMD_EXCEPT;
break;
default:
elog(ERROR, "unrecognized set op: %d", (int) op->op);
cmd = SETOPCMD_INTERSECT; /* keep compiler quiet */
break;
}
path = (Path *) create_setop_path(root,
result_rel,
path,
cmd,
use_hash ? SETOP_HASHED : SETOP_SORTED,
groupList,
list_length(op->colTypes) + 1,
use_hash ? firstFlag : -1,
dNumGroups,
dNumOutputRows);
if (pNumGroups)
*pNumGroups = dNumGroups;
return path;
}
/*
* Pull up children of a UNION node that are identically-propertied UNIONs.
*
* NOTE: we can also pull a UNION ALL up into a UNION, since the distinct
* output rows will be lost anyway.
*
* NOTE: currently, we ignore collations while determining if a child has
* the same properties. This is semantically sound only so long as all
* collations have the same notion of equality. It is valid from an
* implementation standpoint because we don't care about the ordering of
* a UNION child's result: UNION ALL results are always unordered, and
* generate_union_path will force a fresh sort if the top level is a UNION.
*/
static List *
recurse_union_children(Node *setOp, PlannerInfo *root,
SetOperationStmt *top_union,
List *refnames_tlist,
List **tlist_list)
{
List *result;
List *child_tlist;
if (IsA(setOp, SetOperationStmt))
{
SetOperationStmt *op = (SetOperationStmt *) setOp;
if (op->op == top_union->op &&
(op->all == top_union->all || op->all) &&
equal(op->colTypes, top_union->colTypes))
{
/* Same UNION, so fold children into parent's subpath list */
List *child_tlists1;
List *child_tlists2;
result = list_concat(recurse_union_children(op->larg, root,
top_union,
refnames_tlist,
&child_tlists1),
recurse_union_children(op->rarg, root,
top_union,
refnames_tlist,
&child_tlists2));
*tlist_list = list_concat(child_tlists1, child_tlists2);
return result;
}
}
/*
* Not same, so plan this child separately.
*
* Note we disallow any resjunk columns in child results. This is
* necessary since the Append node that implements the union won't do any
* projection, and upper levels will get confused if some of our output
* tuples have junk and some don't. This case only arises when we have an
* EXCEPT or INTERSECT as child, else there won't be resjunk anyway.
*/
result = list_make1(recurse_set_operations(setOp, root,
top_union->colTypes,
top_union->colCollations,
false, -1,
refnames_tlist,
&child_tlist,
NULL));
*tlist_list = list_make1(child_tlist);
return result;
}
/*
* Add nodes to the given path tree to unique-ify the result of a UNION.
*/
static Path *
make_union_unique(SetOperationStmt *op, Path *path, List *tlist,
PlannerInfo *root)
{
RelOptInfo *result_rel = fetch_upper_rel(root, UPPERREL_SETOP, NULL);
List *groupList;
double dNumGroups;
/* Identify the grouping semantics */
groupList = generate_setop_grouplist(op, tlist);
/*
* XXX for the moment, take the number of distinct groups as equal to the
* total input size, ie, the worst case. This is too conservative, but we
* don't want to risk having the hashtable overrun memory; also, it's not
* clear how to get a decent estimate of the true size. One should note
* as well the propensity of novices to write UNION rather than UNION ALL
* even when they don't expect any duplicates...
*/
dNumGroups = path->rows;
/* Decide whether to hash or sort */
if (choose_hashed_setop(root, groupList, path,
dNumGroups, dNumGroups,
"UNION"))
{
/* Hashed aggregate plan --- no sort needed */
path = (Path *) create_agg_path(root,
result_rel,
path,
create_pathtarget(root, tlist),
AGG_HASHED,
AGGSPLIT_SIMPLE,
groupList,
NIL,
NULL,
dNumGroups);
}
else
{
/* Sort and Unique */
if (groupList)
path = (Path *)
create_sort_path(root,
result_rel,
path,
make_pathkeys_for_sortclauses(root,
groupList,
tlist),
-1.0);
/* We have to manually jam the right tlist into the path; ick */
path->pathtarget = create_pathtarget(root, tlist);
path = (Path *) create_upper_unique_path(root,
result_rel,
path,
list_length(path->pathkeys),
dNumGroups);
}
return path;
}
/*
* choose_hashed_setop - should we use hashing for a set operation?
*/
static bool
choose_hashed_setop(PlannerInfo *root, List *groupClauses,
Path *input_path,
double dNumGroups, double dNumOutputRows,
const char *construct)
{
int numGroupCols = list_length(groupClauses);
bool can_sort;
bool can_hash;
Size hashentrysize;
Path hashed_p;
Path sorted_p;
double tuple_fraction;
/* Check whether the operators support sorting or hashing */
can_sort = grouping_is_sortable(groupClauses);
can_hash = grouping_is_hashable(groupClauses);
if (can_hash && can_sort)
{
/* we have a meaningful choice to make, continue ... */
}
else if (can_hash)
return true;
else if (can_sort)
return false;
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
/* translator: %s is UNION, INTERSECT, or EXCEPT */
errmsg("could not implement %s", construct),
errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
/* Prefer sorting when enable_hashagg is off */
if (!enable_hashagg)
return false;
/*
* Don't do it if it doesn't look like the hashtable will fit into
* work_mem.
*/
hashentrysize = MAXALIGN(input_path->pathtarget->width) + MAXALIGN(SizeofMinimalTupleHeader);
if (hashentrysize * dNumGroups > work_mem * 1024L)
return false;
/*
* See if the estimated cost is no more than doing it the other way.
*
* We need to consider input_plan + hashagg versus input_plan + sort +
* group. Note that the actual result plan might involve a SetOp or
* Unique node, not Agg or Group, but the cost estimates for Agg and Group
* should be close enough for our purposes here.
*
* These path variables are dummies that just hold cost fields; we don't
* make actual Paths for these steps.
*/
cost_agg(&hashed_p, root, AGG_HASHED, NULL,
numGroupCols, dNumGroups,
NIL,
input_path->startup_cost, input_path->total_cost,
input_path->rows);
/*
* Now for the sorted case. Note that the input is *always* unsorted,
* since it was made by appending unrelated sub-relations together.
*/
sorted_p.startup_cost = input_path->startup_cost;
sorted_p.total_cost = input_path->total_cost;
/* XXX cost_sort doesn't actually look at pathkeys, so just pass NIL */
cost_sort(&sorted_p, root, NIL, sorted_p.total_cost,
input_path->rows, input_path->pathtarget->width,
0.0, work_mem, -1.0);
cost_group(&sorted_p, root, numGroupCols, dNumGroups,
NIL,
sorted_p.startup_cost, sorted_p.total_cost,
input_path->rows);
/*
* Now make the decision using the top-level tuple fraction. First we
* have to convert an absolute count (LIMIT) into fractional form.
*/
tuple_fraction = root->tuple_fraction;
if (tuple_fraction >= 1.0)
tuple_fraction /= dNumOutputRows;
if (compare_fractional_path_costs(&hashed_p, &sorted_p,
tuple_fraction) < 0)
{
/* Hashed is cheaper, so use it */
return true;
}
return false;
}
/*
* Generate targetlist for a set-operation plan node
*
* colTypes: OID list of set-op's result column datatypes
* colCollations: OID list of set-op's result column collations
* flag: -1 if no flag column needed, 0 or 1 to create a const flag column
* varno: varno to use in generated Vars
* hack_constants: true to copy up constants (see comments in code)
* input_tlist: targetlist of this node's input node
* refnames_tlist: targetlist to take column names from
*/
static List *
generate_setop_tlist(List *colTypes, List *colCollations,
int flag,
Index varno,
bool hack_constants,
List *input_tlist,
List *refnames_tlist)
{
List *tlist = NIL;
int resno = 1;
ListCell *ctlc,
*cclc,
*itlc,
*rtlc;
TargetEntry *tle;
Node *expr;
/* there's no forfour() so we must chase one list manually */
rtlc = list_head(refnames_tlist);
forthree(ctlc, colTypes, cclc, colCollations, itlc, input_tlist)
{
Oid colType = lfirst_oid(ctlc);
Oid colColl = lfirst_oid(cclc);
TargetEntry *inputtle = (TargetEntry *) lfirst(itlc);
TargetEntry *reftle = (TargetEntry *) lfirst(rtlc);
rtlc = lnext(rtlc);
Assert(inputtle->resno == resno);
Assert(reftle->resno == resno);
Assert(!inputtle->resjunk);
Assert(!reftle->resjunk);
/*
* Generate columns referencing input columns and having appropriate
* data types and column names. Insert datatype coercions where
* necessary.
*
* HACK: constants in the input's targetlist are copied up as-is
* rather than being referenced as subquery outputs. This is mainly
* to ensure that when we try to coerce them to the output column's
* datatype, the right things happen for UNKNOWN constants. But do
* this only at the first level of subquery-scan plans; we don't want
* phony constants appearing in the output tlists of upper-level
* nodes!
*/
if (hack_constants && inputtle->expr && IsA(inputtle->expr, Const))
expr = (Node *) inputtle->expr;
else
expr = (Node *) makeVar(varno,
inputtle->resno,
exprType((Node *) inputtle->expr),
exprTypmod((Node *) inputtle->expr),
exprCollation((Node *) inputtle->expr),
0);
if (exprType(expr) != colType)
{
/*
* Note: it's not really cool to be applying coerce_to_common_type
* here; one notable point is that assign_expr_collations never
* gets run on any generated nodes. For the moment that's not a
* problem because we force the correct exposed collation below.
* It would likely be best to make the parser generate the correct
* output tlist for every set-op to begin with, though.
*/
expr = coerce_to_common_type(NULL, /* no UNKNOWNs here */
expr,
colType,
"UNION/INTERSECT/EXCEPT");
}
/*
* Ensure the tlist entry's exposed collation matches the set-op. This
* is necessary because plan_set_operations() reports the result
* ordering as a list of SortGroupClauses, which don't carry collation
* themselves but just refer to tlist entries. If we don't show the
* right collation then planner.c might do the wrong thing in
* higher-level queries.
*
* Note we use RelabelType, not CollateExpr, since this expression
* will reach the executor without any further processing.
*/
if (exprCollation(expr) != colColl)
{
expr = (Node *) makeRelabelType((Expr *) expr,
exprType(expr),
exprTypmod(expr),
colColl,
COERCE_IMPLICIT_CAST);
}
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup(reftle->resname),
false);
/*
* By convention, all non-resjunk columns in a setop tree have
* ressortgroupref equal to their resno. In some cases the ref isn't
* needed, but this is a cleaner way than modifying the tlist later.
*/
tle->ressortgroupref = tle->resno;
tlist = lappend(tlist, tle);
}
if (flag >= 0)
{
/* Add a resjunk flag column */
/* flag value is the given constant */
expr = (Node *) makeConst(INT4OID,
-1,
InvalidOid,
sizeof(int32),
Int32GetDatum(flag),
false,
true);
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup("flag"),
true);
tlist = lappend(tlist, tle);
}
return tlist;
}
/*
* Generate targetlist for a set-operation Append node
*
* colTypes: OID list of set-op's result column datatypes
* colCollations: OID list of set-op's result column collations
* flag: true to create a flag column copied up from subplans
* input_tlists: list of tlists for sub-plans of the Append
* refnames_tlist: targetlist to take column names from
*
* The entries in the Append's targetlist should always be simple Vars;
* we just have to make sure they have the right datatypes/typmods/collations.
* The Vars are always generated with varno 0.
*
* XXX a problem with the varno-zero approach is that set_pathtarget_cost_width
* cannot figure out a realistic width for the tlist we make here. But we
* ought to refactor this code to produce a PathTarget directly, anyway.
*/
static List *
generate_append_tlist(List *colTypes, List *colCollations,
bool flag,
List *input_tlists,
List *refnames_tlist)
{
List *tlist = NIL;
int resno = 1;
ListCell *curColType;
ListCell *curColCollation;
ListCell *ref_tl_item;
int colindex;
TargetEntry *tle;
Node *expr;
ListCell *tlistl;
int32 *colTypmods;
/*
* First extract typmods to use.
*
* If the inputs all agree on type and typmod of a particular column, use
* that typmod; else use -1.
*/
colTypmods = (int32 *) palloc(list_length(colTypes) * sizeof(int32));
foreach(tlistl, input_tlists)
{
List *subtlist = (List *) lfirst(tlistl);
ListCell *subtlistl;
curColType = list_head(colTypes);
colindex = 0;
foreach(subtlistl, subtlist)
{
TargetEntry *subtle = (TargetEntry *) lfirst(subtlistl);
if (subtle->resjunk)
continue;
Assert(curColType != NULL);
if (exprType((Node *) subtle->expr) == lfirst_oid(curColType))
{
/* If first subplan, copy the typmod; else compare */
int32 subtypmod = exprTypmod((Node *) subtle->expr);
if (tlistl == list_head(input_tlists))
colTypmods[colindex] = subtypmod;
else if (subtypmod != colTypmods[colindex])
colTypmods[colindex] = -1;
}
else
{
/* types disagree, so force typmod to -1 */
colTypmods[colindex] = -1;
}
curColType = lnext(curColType);
colindex++;
}
Assert(curColType == NULL);
}
/*
* Now we can build the tlist for the Append.
*/
colindex = 0;
forthree(curColType, colTypes, curColCollation, colCollations,
ref_tl_item, refnames_tlist)
{
Oid colType = lfirst_oid(curColType);
int32 colTypmod = colTypmods[colindex++];
Oid colColl = lfirst_oid(curColCollation);
TargetEntry *reftle = (TargetEntry *) lfirst(ref_tl_item);
Assert(reftle->resno == resno);
Assert(!reftle->resjunk);
expr = (Node *) makeVar(0,
resno,
colType,
colTypmod,
colColl,
0);
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup(reftle->resname),
false);
/*
* By convention, all non-resjunk columns in a setop tree have
* ressortgroupref equal to their resno. In some cases the ref isn't
* needed, but this is a cleaner way than modifying the tlist later.
*/
tle->ressortgroupref = tle->resno;
tlist = lappend(tlist, tle);
}
if (flag)
{
/* Add a resjunk flag column */
/* flag value is shown as copied up from subplan */
expr = (Node *) makeVar(0,
resno,
INT4OID,
-1,
InvalidOid,
0);
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup("flag"),
true);
tlist = lappend(tlist, tle);
}
pfree(colTypmods);
return tlist;
}
/*
* generate_setop_grouplist
* Build a SortGroupClause list defining the sort/grouping properties
* of the setop's output columns.
*
* Parse analysis already determined the properties and built a suitable
* list, except that the entries do not have sortgrouprefs set because
* the parser output representation doesn't include a tlist for each
* setop. So what we need to do here is copy that list and install
* proper sortgrouprefs into it (copying those from the targetlist).
*/
static List *
generate_setop_grouplist(SetOperationStmt *op, List *targetlist)
{
List *grouplist = copyObject(op->groupClauses);
ListCell *lg;
ListCell *lt;
lg = list_head(grouplist);
foreach(lt, targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lt);
SortGroupClause *sgc;
if (tle->resjunk)
{
/* resjunk columns should not have sortgrouprefs */
Assert(tle->ressortgroupref == 0);
continue; /* ignore resjunk columns */
}
/* non-resjunk columns should have sortgroupref = resno */
Assert(tle->ressortgroupref == tle->resno);
/* non-resjunk columns should have grouping clauses */
Assert(lg != NULL);
sgc = (SortGroupClause *) lfirst(lg);
lg = lnext(lg);
Assert(sgc->tleSortGroupRef == 0);
sgc->tleSortGroupRef = tle->ressortgroupref;
}
Assert(lg == NULL);
return grouplist;
}
/*
* expand_inherited_tables
* Expand each rangetable entry that represents an inheritance set
* into an "append relation". At the conclusion of this process,
* the "inh" flag is set in all and only those RTEs that are append
* relation parents.
*/
void
expand_inherited_tables(PlannerInfo *root)
{
Index nrtes;
Index rti;
ListCell *rl;
/*
* expand_inherited_rtentry may add RTEs to parse->rtable. The function is
* expected to recursively handle any RTEs that it creates with inh=true.
* So just scan as far as the original end of the rtable list.
*/
nrtes = list_length(root->parse->rtable);
rl = list_head(root->parse->rtable);
for (rti = 1; rti <= nrtes; rti++)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(rl);
expand_inherited_rtentry(root, rte, rti);
rl = lnext(rl);
}
}
/*
* expand_inherited_rtentry
* Check whether a rangetable entry represents an inheritance set.
* If so, add entries for all the child tables to the query's
* rangetable, and build AppendRelInfo nodes for all the child tables
* and add them to root->append_rel_list. If not, clear the entry's
* "inh" flag to prevent later code from looking for AppendRelInfos.
*
* Note that the original RTE is considered to represent the whole
* inheritance set. The first of the generated RTEs is an RTE for the same
* table, but with inh = false, to represent the parent table in its role
* as a simple member of the inheritance set.
*
* A childless table is never considered to be an inheritance set. For
* regular inheritance, a parent RTE must always have at least two associated
* AppendRelInfos: one corresponding to the parent table as a simple member of
* inheritance set and one or more corresponding to the actual children.
* Since a partitioned table is not scanned, it might have only one associated
* AppendRelInfo.
*/
static void
expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
{
Query *parse = root->parse;
Oid parentOID;
PlanRowMark *oldrc;
Relation oldrelation;
LOCKMODE lockmode;
List *inhOIDs;
ListCell *l;
/* Does RT entry allow inheritance? */
if (!rte->inh)
return;
/* Ignore any already-expanded UNION ALL nodes */
if (rte->rtekind != RTE_RELATION)
{
Assert(rte->rtekind == RTE_SUBQUERY);
return;
}
/* Fast path for common case of childless table */
parentOID = rte->relid;
if (!has_subclass(parentOID))
{
/* Clear flag before returning */
rte->inh = false;
return;
}
/*
* The rewriter should already have obtained an appropriate lock on each
* relation named in the query. However, for each child relation we add
* to the query, we must obtain an appropriate lock, because this will be
* the first use of those relations in the parse/rewrite/plan pipeline.
*
* If the parent relation is the query's result relation, then we need
* RowExclusiveLock. Otherwise, if it's accessed FOR UPDATE/SHARE, we
* need RowShareLock; otherwise AccessShareLock. We can't just grab
* AccessShareLock because then the executor would be trying to upgrade
* the lock, leading to possible deadlocks. (This code should match the
* parser and rewriter.)
*/
oldrc = get_plan_rowmark(root->rowMarks, rti);
if (rti == parse->resultRelation)
lockmode = RowExclusiveLock;
else if (oldrc && RowMarkRequiresRowShareLock(oldrc->markType))
lockmode = RowShareLock;
else
lockmode = AccessShareLock;
/* Scan for all members of inheritance set, acquire needed locks */
inhOIDs = find_all_inheritors(parentOID, lockmode, NULL);
/*
* Check that there's at least one descendant, else treat as no-child
* case. This could happen despite above has_subclass() check, if table
* once had a child but no longer does.
*/
if (list_length(inhOIDs) < 2)
{
/* Clear flag before returning */
rte->inh = false;
return;
}
/*
* If parent relation is selected FOR UPDATE/SHARE, we need to mark its
* PlanRowMark as isParent = true, and generate a new PlanRowMark for each
* child.
*/
if (oldrc)
oldrc->isParent = true;
/*
* Must open the parent relation to examine its tupdesc. We need not lock
* it; we assume the rewriter already did.
*/
oldrelation = heap_open(parentOID, NoLock);
/* Scan the inheritance set and expand it */
if (RelationGetPartitionDesc(oldrelation) != NULL)
{
List *partitioned_child_rels = NIL;
Assert(rte->relkind == RELKIND_PARTITIONED_TABLE);
/*
* If this table has partitions, recursively expand them in the order
* in which they appear in the PartitionDesc.
*/
expand_partitioned_rtentry(root, rte, rti, oldrelation, oldrc,
lockmode, &root->append_rel_list,
&partitioned_child_rels);
/*
* We keep a list of objects in root, each of which maps a root
* partitioned parent RT index to the list of RT indexes of descendant
* partitioned child tables. When creating an Append or a ModifyTable
* path for the parent, we copy the child RT index list verbatim to
* the path so that it could be carried over to the executor so that
* the latter could identify the partitioned child tables.
*/
if (rte->inh && partitioned_child_rels != NIL)
{
PartitionedChildRelInfo *pcinfo;
pcinfo = makeNode(PartitionedChildRelInfo);
pcinfo->parent_relid = rti;
pcinfo->child_rels = partitioned_child_rels;
root->pcinfo_list = lappend(root->pcinfo_list, pcinfo);
}
}
else
{
List *appinfos = NIL;
RangeTblEntry *childrte;
Index childRTindex;
/*
* This table has no partitions. Expand any plain inheritance
* children in the order the OIDs were returned by
* find_all_inheritors.
*/
foreach(l, inhOIDs)
{
Oid childOID = lfirst_oid(l);
Relation newrelation;
/* Open rel if needed; we already have required locks */
if (childOID != parentOID)
newrelation = heap_open(childOID, NoLock);
else
newrelation = oldrelation;
/*
* It is possible that the parent table has children that are temp
* tables of other backends. We cannot safely access such tables
* (because of buffering issues), and the best thing to do seems
* to be to silently ignore them.
*/
if (childOID != parentOID && RELATION_IS_OTHER_TEMP(newrelation))
{
heap_close(newrelation, lockmode);
continue;
}
expand_single_inheritance_child(root, rte, rti, oldrelation, oldrc,
newrelation,
&appinfos, &childrte,
&childRTindex);
/* Close child relations, but keep locks */
if (childOID != parentOID)
heap_close(newrelation, NoLock);
}
/*
* If all the children were temp tables, pretend it's a
* non-inheritance situation; we don't need Append node in that case.
* The duplicate RTE we added for the parent table is harmless, so we
* don't bother to get rid of it; ditto for the useless PlanRowMark
* node.
*/
if (list_length(appinfos) < 2)
rte->inh = false;
else
root->append_rel_list = list_concat(root->append_rel_list,
appinfos);
}
heap_close(oldrelation, NoLock);
}
/*
* expand_partitioned_rtentry
* Recursively expand an RTE for a partitioned table.
*
* Note that RelationGetPartitionDispatchInfo will expand partitions in the
* same order as this code.
*/
static void
expand_partitioned_rtentry(PlannerInfo *root, RangeTblEntry *parentrte,
Index parentRTindex, Relation parentrel,
PlanRowMark *top_parentrc, LOCKMODE lockmode,
List **appinfos, List **partitioned_child_rels)
{
int i;
RangeTblEntry *childrte;
Index childRTindex;
bool has_child = false;
PartitionDesc partdesc = RelationGetPartitionDesc(parentrel);
check_stack_depth();
/* A partitioned table should always have a partition descriptor. */
Assert(partdesc);
Assert(parentrte->inh);
/* First expand the partitioned table itself. */
expand_single_inheritance_child(root, parentrte, parentRTindex, parentrel,
top_parentrc, parentrel,
appinfos, &childrte, &childRTindex);
/*
* The partitioned table does not have data for itself but still need to
* be locked. Update given list of partitioned children with RTI of this
* partitioned relation.
*/
*partitioned_child_rels = lappend_int(*partitioned_child_rels,
childRTindex);
for (i = 0; i < partdesc->nparts; i++)
{
Oid childOID = partdesc->oids[i];
Relation childrel;
/* Open rel; we already have required locks */
childrel = heap_open(childOID, NoLock);
/* As in expand_inherited_rtentry, skip non-local temp tables */
if (RELATION_IS_OTHER_TEMP(childrel))
{
heap_close(childrel, lockmode);
continue;
}
/* We have a real partition. */
has_child = true;
expand_single_inheritance_child(root, parentrte, parentRTindex,
parentrel, top_parentrc, childrel,
appinfos, &childrte, &childRTindex);
/* If this child is itself partitioned, recurse */
if (childrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
expand_partitioned_rtentry(root, childrte, childRTindex,
childrel, top_parentrc, lockmode,
appinfos, partitioned_child_rels);
/* Close child relation, but keep locks */
heap_close(childrel, NoLock);
}
/*
* If the partitioned table has no partitions or all the partitions are
* temporary tables from other backends, treat this as non-inheritance
* case.
*/
if (!has_child)
parentrte->inh = false;
}
/*
* expand_single_inheritance_child
* Expand a single inheritance child, if needed.
*
* If this is a temp table of another backend, we'll return without doing
* anything at all. Otherwise, build a RangeTblEntry and an AppendRelInfo, if
* appropriate, plus maybe a PlanRowMark.
*
* We now expand the partition hierarchy level by level, creating a
* corresponding hierarchy of AppendRelInfos and RelOptInfos, where each
* partitioned descendant acts as a parent of its immediate partitions.
* (This is a difference from what older versions of PostgreSQL did and what
* is still done in the case of table inheritance for unpartitioned tables,
* where the hierarchy is flattened during RTE expansion.)
*
* PlanRowMarks still carry the top-parent's RTI, and the top-parent's
* allMarkTypes field still accumulates values from all descendents.
*
* "parentrte" and "parentRTindex" are immediate parent's RTE and
* RTI. "top_parentrc" is top parent's PlanRowMark.
*
* The child RangeTblEntry and its RTI are returned in "childrte_p" and
* "childRTindex_p" resp.
*/
static void
expand_single_inheritance_child(PlannerInfo *root, RangeTblEntry *parentrte,
Index parentRTindex, Relation parentrel,
PlanRowMark *top_parentrc, Relation childrel,
List **appinfos, RangeTblEntry **childrte_p,
Index *childRTindex_p)
{
Query *parse = root->parse;
Oid parentOID = RelationGetRelid(parentrel);
Oid childOID = RelationGetRelid(childrel);
RangeTblEntry *childrte;
Index childRTindex;
AppendRelInfo *appinfo;
/*
* Build an RTE for the child, and attach to query's rangetable list. We
* copy most fields of the parent's RTE, but replace relation OID and
* relkind, and set inh = false. Also, set requiredPerms to zero since
* all required permissions checks are done on the original RTE. Likewise,
* set the child's securityQuals to empty, because we only want to apply
* the parent's RLS conditions regardless of what RLS properties
* individual children may have. (This is an intentional choice to make
* inherited RLS work like regular permissions checks.) The parent
* securityQuals will be propagated to children along with other base
* restriction clauses, so we don't need to do it here.
*/
childrte = copyObject(parentrte);
*childrte_p = childrte;
childrte->relid = childOID;
childrte->relkind = childrel->rd_rel->relkind;
/* A partitioned child will need to be expanded further. */
if (childOID != parentOID &&
childrte->relkind == RELKIND_PARTITIONED_TABLE)
childrte->inh = true;
else
childrte->inh = false;
childrte->requiredPerms = 0;
childrte->securityQuals = NIL;
parse->rtable = lappend(parse->rtable, childrte);
childRTindex = list_length(parse->rtable);
*childRTindex_p = childRTindex;
/*
* We need an AppendRelInfo if paths will be built for the child RTE. If
* childrte->inh is true, then we'll always need to generate append paths
* for it. If childrte->inh is false, we must scan it if it's not a
* partitioned table; but if it is a partitioned table, then it never has
* any data of its own and need not be scanned.
*/
if (childrte->relkind != RELKIND_PARTITIONED_TABLE || childrte->inh)
{
appinfo = makeNode(AppendRelInfo);
appinfo->parent_relid = parentRTindex;
appinfo->child_relid = childRTindex;
appinfo->parent_reltype = parentrel->rd_rel->reltype;
appinfo->child_reltype = childrel->rd_rel->reltype;
make_inh_translation_list(parentrel, childrel, childRTindex,
&appinfo->translated_vars);
appinfo->parent_reloid = parentOID;
*appinfos = lappend(*appinfos, appinfo);
/*
* Translate the column permissions bitmaps to the child's attnums (we
* have to build the translated_vars list before we can do this). But
* if this is the parent table, leave copyObject's result alone.
*
* Note: we need to do this even though the executor won't run any
* permissions checks on the child RTE. The insertedCols/updatedCols
* bitmaps may be examined for trigger-firing purposes.
*/
if (childOID != parentOID)
{
childrte->selectedCols = translate_col_privs(parentrte->selectedCols,
appinfo->translated_vars);
childrte->insertedCols = translate_col_privs(parentrte->insertedCols,
appinfo->translated_vars);
childrte->updatedCols = translate_col_privs(parentrte->updatedCols,
appinfo->translated_vars);
}
}
/*
* Build a PlanRowMark if parent is marked FOR UPDATE/SHARE.
*/
if (top_parentrc)
{
PlanRowMark *childrc = makeNode(PlanRowMark);
childrc->rti = childRTindex;
childrc->prti = top_parentrc->rti;
childrc->rowmarkId = top_parentrc->rowmarkId;
/* Reselect rowmark type, because relkind might not match parent */
childrc->markType = select_rowmark_type(childrte,
top_parentrc->strength);
childrc->allMarkTypes = (1 << childrc->markType);
childrc->strength = top_parentrc->strength;
childrc->waitPolicy = top_parentrc->waitPolicy;
/*
* We mark RowMarks for partitioned child tables as parent RowMarks so
* that the executor ignores them (except their existence means that
* the child tables be locked using appropriate mode).
*/
childrc->isParent = (childrte->relkind == RELKIND_PARTITIONED_TABLE);
/* Include child's rowmark type in top parent's allMarkTypes */
top_parentrc->allMarkTypes |= childrc->allMarkTypes;
root->rowMarks = lappend(root->rowMarks, childrc);
}
}
/*
* make_inh_translation_list
* Build the list of translations from parent Vars to child Vars for
* an inheritance child.
*
* For paranoia's sake, we match type/collation as well as attribute name.
*/
static void
make_inh_translation_list(Relation oldrelation, Relation newrelation,
Index newvarno,
List **translated_vars)
{
List *vars = NIL;
TupleDesc old_tupdesc = RelationGetDescr(oldrelation);
TupleDesc new_tupdesc = RelationGetDescr(newrelation);
int oldnatts = old_tupdesc->natts;
int newnatts = new_tupdesc->natts;
int old_attno;
for (old_attno = 0; old_attno < oldnatts; old_attno++)
{
Form_pg_attribute att;
char *attname;
Oid atttypid;
int32 atttypmod;
Oid attcollation;
int new_attno;
att = TupleDescAttr(old_tupdesc, old_attno);
if (att->attisdropped)
{
/* Just put NULL into this list entry */
vars = lappend(vars, NULL);
continue;
}
attname = NameStr(att->attname);
atttypid = att->atttypid;
atttypmod = att->atttypmod;
attcollation = att->attcollation;
/*
* When we are generating the "translation list" for the parent table
* of an inheritance set, no need to search for matches.
*/
if (oldrelation == newrelation)
{
vars = lappend(vars, makeVar(newvarno,
(AttrNumber) (old_attno + 1),
atttypid,
atttypmod,
attcollation,
0));
continue;
}
/*
* Otherwise we have to search for the matching column by name.
* There's no guarantee it'll have the same column position, because
* of cases like ALTER TABLE ADD COLUMN and multiple inheritance.
* However, in simple cases it will be the same column number, so try
* that before we go groveling through all the columns.
*
* Note: the test for (att = ...) != NULL cannot fail, it's just a
* notational device to include the assignment into the if-clause.
*/
if (old_attno < newnatts &&
(att = TupleDescAttr(new_tupdesc, old_attno)) != NULL &&
!att->attisdropped && att->attinhcount != 0 &&
strcmp(attname, NameStr(att->attname)) == 0)
new_attno = old_attno;
else
{
for (new_attno = 0; new_attno < newnatts; new_attno++)
{
att = TupleDescAttr(new_tupdesc, new_attno);
if (!att->attisdropped && att->attinhcount != 0 &&
strcmp(attname, NameStr(att->attname)) == 0)
break;
}
if (new_attno >= newnatts)
elog(ERROR, "could not find inherited attribute \"%s\" of relation \"%s\"",
attname, RelationGetRelationName(newrelation));
}
/* Found it, check type and collation match */
if (atttypid != att->atttypid || atttypmod != att->atttypmod)
elog(ERROR, "attribute \"%s\" of relation \"%s\" does not match parent's type",
attname, RelationGetRelationName(newrelation));
if (attcollation != att->attcollation)
elog(ERROR, "attribute \"%s\" of relation \"%s\" does not match parent's collation",
attname, RelationGetRelationName(newrelation));
vars = lappend(vars, makeVar(newvarno,
(AttrNumber) (new_attno + 1),
atttypid,
atttypmod,
attcollation,
0));
}
*translated_vars = vars;
}
/*
* translate_col_privs
* Translate a bitmapset representing per-column privileges from the
* parent rel's attribute numbering to the child's.
*
* The only surprise here is that we don't translate a parent whole-row
* reference into a child whole-row reference. That would mean requiring
* permissions on all child columns, which is overly strict, since the
* query is really only going to reference the inherited columns. Instead
* we set the per-column bits for all inherited columns.
*/
static Bitmapset *
translate_col_privs(const Bitmapset *parent_privs,
List *translated_vars)
{
Bitmapset *child_privs = NULL;
bool whole_row;
int attno;
ListCell *lc;
/* System attributes have the same numbers in all tables */
for (attno = FirstLowInvalidHeapAttributeNumber + 1; attno < 0; attno++)
{
if (bms_is_member(attno - FirstLowInvalidHeapAttributeNumber,
parent_privs))
child_privs = bms_add_member(child_privs,
attno - FirstLowInvalidHeapAttributeNumber);
}
/* Check if parent has whole-row reference */
whole_row = bms_is_member(InvalidAttrNumber - FirstLowInvalidHeapAttributeNumber,
parent_privs);
/* And now translate the regular user attributes, using the vars list */
attno = InvalidAttrNumber;
foreach(lc, translated_vars)
{
Var *var = lfirst_node(Var, lc);
attno++;
if (var == NULL) /* ignore dropped columns */
continue;
if (whole_row ||
bms_is_member(attno - FirstLowInvalidHeapAttributeNumber,
parent_privs))
child_privs = bms_add_member(child_privs,
var->varattno - FirstLowInvalidHeapAttributeNumber);
}
return child_privs;
}
/*
* adjust_appendrel_attrs
* Copy the specified query or expression and translate Vars referring to a
* parent rel to refer to the corresponding child rel instead. We also
* update rtindexes appearing outside Vars, such as resultRelation and
* jointree relids.
*
* Note: this is only applied after conversion of sublinks to subplans,
* so we don't need to cope with recursion into sub-queries.
*
* Note: this is not hugely different from what pullup_replace_vars() does;
* maybe we should try to fold the two routines together.
*/
Node *
adjust_appendrel_attrs(PlannerInfo *root, Node *node, int nappinfos,
AppendRelInfo **appinfos)
{
Node *result;
adjust_appendrel_attrs_context context;
context.root = root;
context.nappinfos = nappinfos;
context.appinfos = appinfos;
/* If there's nothing to adjust, don't call this function. */
Assert(nappinfos >= 1 && appinfos != NULL);
/*
* Must be prepared to start with a Query or a bare expression tree.
*/
if (node && IsA(node, Query))
{
Query *newnode;
int cnt;
newnode = query_tree_mutator((Query *) node,
adjust_appendrel_attrs_mutator,
(void *) &context,
QTW_IGNORE_RC_SUBQUERIES);
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
if (newnode->resultRelation == appinfo->parent_relid)
{
newnode->resultRelation = appinfo->child_relid;
/* Fix tlist resnos too, if it's inherited UPDATE */
if (newnode->commandType == CMD_UPDATE)
newnode->targetList =
adjust_inherited_tlist(newnode->targetList,
appinfo);
break;
}
}
result = (Node *) newnode;
}
else
result = adjust_appendrel_attrs_mutator(node, &context);
return result;
}
static Node *
adjust_appendrel_attrs_mutator(Node *node,
adjust_appendrel_attrs_context *context)
{
AppendRelInfo **appinfos = context->appinfos;
int nappinfos = context->nappinfos;
int cnt;
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
Var *var = (Var *) copyObject(node);
AppendRelInfo *appinfo = NULL;
for (cnt = 0; cnt < nappinfos; cnt++)
{
if (var->varno == appinfos[cnt]->parent_relid)
{
appinfo = appinfos[cnt];
break;
}
}
if (var->varlevelsup == 0 && appinfo)
{
var->varno = appinfo->child_relid;
var->varnoold = appinfo->child_relid;
if (var->varattno > 0)
{
Node *newnode;
if (var->varattno > list_length(appinfo->translated_vars))
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
var->varattno, get_rel_name(appinfo->parent_reloid));
newnode = copyObject(list_nth(appinfo->translated_vars,
var->varattno - 1));
if (newnode == NULL)
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
var->varattno, get_rel_name(appinfo->parent_reloid));
return newnode;
}
else if (var->varattno == 0)
{
/*
* Whole-row Var: if we are dealing with named rowtypes, we
* can use a whole-row Var for the child table plus a coercion
* step to convert the tuple layout to the parent's rowtype.
* Otherwise we have to generate a RowExpr.
*/
if (OidIsValid(appinfo->child_reltype))
{
Assert(var->vartype == appinfo->parent_reltype);
if (appinfo->parent_reltype != appinfo->child_reltype)
{
ConvertRowtypeExpr *r = makeNode(ConvertRowtypeExpr);
r->arg = (Expr *) var;
r->resulttype = appinfo->parent_reltype;
r->convertformat = COERCE_IMPLICIT_CAST;
r->location = -1;
/* Make sure the Var node has the right type ID, too */
var->vartype = appinfo->child_reltype;
return (Node *) r;
}
}
else
{
/*
* Build a RowExpr containing the translated variables.
*
* In practice var->vartype will always be RECORDOID here,
* so we need to come up with some suitable column names.
* We use the parent RTE's column names.
*
* Note: we can't get here for inheritance cases, so there
* is no need to worry that translated_vars might contain
* some dummy NULLs.
*/
RowExpr *rowexpr;
List *fields;
RangeTblEntry *rte;
rte = rt_fetch(appinfo->parent_relid,
context->root->parse->rtable);
fields = copyObject(appinfo->translated_vars);
rowexpr = makeNode(RowExpr);
rowexpr->args = fields;
rowexpr->row_typeid = var->vartype;
rowexpr->row_format = COERCE_IMPLICIT_CAST;
rowexpr->colnames = copyObject(rte->eref->colnames);
rowexpr->location = -1;
return (Node *) rowexpr;
}
}
/* system attributes don't need any other translation */
}
return (Node *) var;
}
if (IsA(node, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
if (cexpr->cvarno == appinfo->parent_relid)
{
cexpr->cvarno = appinfo->child_relid;
break;
}
}
return (Node *) cexpr;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) copyObject(node);
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
if (rtr->rtindex == appinfo->parent_relid)
{
rtr->rtindex = appinfo->child_relid;
break;
}
}
return (Node *) rtr;
}
if (IsA(node, JoinExpr))
{
/* Copy the JoinExpr node with correct mutation of subnodes */
JoinExpr *j;
AppendRelInfo *appinfo;
j = (JoinExpr *) expression_tree_mutator(node,
adjust_appendrel_attrs_mutator,
(void *) context);
/* now fix JoinExpr's rtindex (probably never happens) */
for (cnt = 0; cnt < nappinfos; cnt++)
{
appinfo = appinfos[cnt];
if (j->rtindex == appinfo->parent_relid)
{
j->rtindex = appinfo->child_relid;
break;
}
}
return (Node *) j;
}
if (IsA(node, PlaceHolderVar))
{
/* Copy the PlaceHolderVar node with correct mutation of subnodes */
PlaceHolderVar *phv;
phv = (PlaceHolderVar *) expression_tree_mutator(node,
adjust_appendrel_attrs_mutator,
(void *) context);
/* now fix PlaceHolderVar's relid sets */
if (phv->phlevelsup == 0)
phv->phrels = adjust_child_relids(phv->phrels, context->nappinfos,
context->appinfos);
return (Node *) phv;
}
/* Shouldn't need to handle planner auxiliary nodes here */
Assert(!IsA(node, SpecialJoinInfo));
Assert(!IsA(node, AppendRelInfo));
Assert(!IsA(node, PlaceHolderInfo));
Assert(!IsA(node, MinMaxAggInfo));
/*
* We have to process RestrictInfo nodes specially. (Note: although
* set_append_rel_pathlist will hide RestrictInfos in the parent's
* baserestrictinfo list from us, it doesn't hide those in joininfo.)
*/
if (IsA(node, RestrictInfo))
{
RestrictInfo *oldinfo = (RestrictInfo *) node;
RestrictInfo *newinfo = makeNode(RestrictInfo);
/* Copy all flat-copiable fields */
memcpy(newinfo, oldinfo, sizeof(RestrictInfo));
/* Recursively fix the clause itself */
newinfo->clause = (Expr *)
adjust_appendrel_attrs_mutator((Node *) oldinfo->clause, context);
/* and the modified version, if an OR clause */
newinfo->orclause = (Expr *)
adjust_appendrel_attrs_mutator((Node *) oldinfo->orclause, context);
/* adjust relid sets too */
newinfo->clause_relids = adjust_child_relids(oldinfo->clause_relids,
context->nappinfos,
context->appinfos);
newinfo->required_relids = adjust_child_relids(oldinfo->required_relids,
context->nappinfos,
context->appinfos);
newinfo->outer_relids = adjust_child_relids(oldinfo->outer_relids,
context->nappinfos,
context->appinfos);
newinfo->nullable_relids = adjust_child_relids(oldinfo->nullable_relids,
context->nappinfos,
context->appinfos);
newinfo->left_relids = adjust_child_relids(oldinfo->left_relids,
context->nappinfos,
context->appinfos);
newinfo->right_relids = adjust_child_relids(oldinfo->right_relids,
context->nappinfos,
context->appinfos);
/*
* Reset cached derivative fields, since these might need to have
* different values when considering the child relation. Note we
* don't reset left_ec/right_ec: each child variable is implicitly
* equivalent to its parent, so still a member of the same EC if any.
*/
newinfo->eval_cost.startup = -1;
newinfo->norm_selec = -1;
newinfo->outer_selec = -1;
newinfo->left_em = NULL;
newinfo->right_em = NULL;
newinfo->scansel_cache = NIL;
newinfo->left_bucketsize = -1;
newinfo->right_bucketsize = -1;
newinfo->left_mcvfreq = -1;
newinfo->right_mcvfreq = -1;
return (Node *) newinfo;
}
/*
* NOTE: we do not need to recurse into sublinks, because they should
* already have been converted to subplans before we see them.
*/
Assert(!IsA(node, SubLink));
Assert(!IsA(node, Query));
return expression_tree_mutator(node, adjust_appendrel_attrs_mutator,
(void *) context);
}
/*
* Substitute child relids for parent relids in a Relid set. The array of
* appinfos specifies the substitutions to be performed.
*/
static Relids
adjust_child_relids(Relids relids, int nappinfos, AppendRelInfo **appinfos)
{
Bitmapset *result = NULL;
int cnt;
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
/* Remove parent, add child */
if (bms_is_member(appinfo->parent_relid, relids))
{
/* Make a copy if we are changing the set. */
if (!result)
result = bms_copy(relids);
result = bms_del_member(result, appinfo->parent_relid);
result = bms_add_member(result, appinfo->child_relid);
}
}
/* If we made any changes, return the modified copy. */
if (result)
return result;
/* Otherwise, return the original set without modification. */
return relids;
}
/*
* Replace any relid present in top_parent_relids with its child in
* child_relids. Members of child_relids can be multiple levels below top
* parent in the partition hierarchy.
*/
Relids
adjust_child_relids_multilevel(PlannerInfo *root, Relids relids,
Relids child_relids, Relids top_parent_relids)
{
AppendRelInfo **appinfos;
int nappinfos;
Relids parent_relids = NULL;
Relids result;
Relids tmp_result = NULL;
int cnt;
/*
* If the given relids set doesn't contain any of the top parent relids,
* it will remain unchanged.
*/
if (!bms_overlap(relids, top_parent_relids))
return relids;
appinfos = find_appinfos_by_relids(root, child_relids, &nappinfos);
/* Construct relids set for the immediate parent of the given child. */
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
parent_relids = bms_add_member(parent_relids, appinfo->parent_relid);
}
/* Recurse if immediate parent is not the top parent. */
if (!bms_equal(parent_relids, top_parent_relids))
{
tmp_result = adjust_child_relids_multilevel(root, relids,
parent_relids,
top_parent_relids);
relids = tmp_result;
}
result = adjust_child_relids(relids, nappinfos, appinfos);
/* Free memory consumed by any intermediate result. */
if (tmp_result)
bms_free(tmp_result);
bms_free(parent_relids);
pfree(appinfos);
return result;
}
/*
* Adjust the targetlist entries of an inherited UPDATE operation
*
* The expressions have already been fixed, but we have to make sure that
* the target resnos match the child table (they may not, in the case of
* a column that was added after-the-fact by ALTER TABLE). In some cases
* this can force us to re-order the tlist to preserve resno ordering.
* (We do all this work in special cases so that preptlist.c is fast for
* the typical case.)
*
* The given tlist has already been through expression_tree_mutator;
* therefore the TargetEntry nodes are fresh copies that it's okay to
* scribble on.
*
* Note that this is not needed for INSERT because INSERT isn't inheritable.
*/
static List *
adjust_inherited_tlist(List *tlist, AppendRelInfo *context)
{
bool changed_it = false;
ListCell *tl;
List *new_tlist;
bool more;
int attrno;
/* This should only happen for an inheritance case, not UNION ALL */
Assert(OidIsValid(context->parent_reloid));
/* Scan tlist and update resnos to match attnums of child rel */
foreach(tl, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tl);
Var *childvar;
if (tle->resjunk)
continue; /* ignore junk items */
/* Look up the translation of this column: it must be a Var */
if (tle->resno <= 0 ||
tle->resno > list_length(context->translated_vars))
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
tle->resno, get_rel_name(context->parent_reloid));
childvar = (Var *) list_nth(context->translated_vars, tle->resno - 1);
if (childvar == NULL || !IsA(childvar, Var))
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
tle->resno, get_rel_name(context->parent_reloid));
if (tle->resno != childvar->varattno)
{
tle->resno = childvar->varattno;
changed_it = true;
}
}
/*
* If we changed anything, re-sort the tlist by resno, and make sure
* resjunk entries have resnos above the last real resno. The sort
* algorithm is a bit stupid, but for such a seldom-taken path, small is
* probably better than fast.
*/
if (!changed_it)
return tlist;
new_tlist = NIL;
more = true;
for (attrno = 1; more; attrno++)
{
more = false;
foreach(tl, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tl);
if (tle->resjunk)
continue; /* ignore junk items */
if (tle->resno == attrno)
new_tlist = lappend(new_tlist, tle);
else if (tle->resno > attrno)
more = true;
}
}
foreach(tl, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tl);
if (!tle->resjunk)
continue; /* here, ignore non-junk items */
tle->resno = attrno;
new_tlist = lappend(new_tlist, tle);
attrno++;
}
return new_tlist;
}
/*
* adjust_appendrel_attrs_multilevel
* Apply Var translations from a toplevel appendrel parent down to a child.
*
* In some cases we need to translate expressions referencing a parent relation
* to reference an appendrel child that's multiple levels removed from it.
*/
Node *
adjust_appendrel_attrs_multilevel(PlannerInfo *root, Node *node,
Relids child_relids,
Relids top_parent_relids)
{
AppendRelInfo **appinfos;
Bitmapset *parent_relids = NULL;
int nappinfos;
int cnt;
Assert(bms_num_members(child_relids) == bms_num_members(top_parent_relids));
appinfos = find_appinfos_by_relids(root, child_relids, &nappinfos);
/* Construct relids set for the immediate parent of given child. */
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
parent_relids = bms_add_member(parent_relids, appinfo->parent_relid);
}
/* Recurse if immediate parent is not the top parent. */
if (!bms_equal(parent_relids, top_parent_relids))
node = adjust_appendrel_attrs_multilevel(root, node, parent_relids,
top_parent_relids);
/* Now translate for this child */
node = adjust_appendrel_attrs(root, node, nappinfos, appinfos);
pfree(appinfos);
return node;
}
/*
* Construct the SpecialJoinInfo for a child-join by translating
* SpecialJoinInfo for the join between parents. left_relids and right_relids
* are the relids of left and right side of the join respectively.
*/
SpecialJoinInfo *
build_child_join_sjinfo(PlannerInfo *root, SpecialJoinInfo *parent_sjinfo,
Relids left_relids, Relids right_relids)
{
SpecialJoinInfo *sjinfo = makeNode(SpecialJoinInfo);
AppendRelInfo **left_appinfos;
int left_nappinfos;
AppendRelInfo **right_appinfos;
int right_nappinfos;
memcpy(sjinfo, parent_sjinfo, sizeof(SpecialJoinInfo));
left_appinfos = find_appinfos_by_relids(root, left_relids,
&left_nappinfos);
right_appinfos = find_appinfos_by_relids(root, right_relids,
&right_nappinfos);
sjinfo->min_lefthand = adjust_child_relids(sjinfo->min_lefthand,
left_nappinfos, left_appinfos);
sjinfo->min_righthand = adjust_child_relids(sjinfo->min_righthand,
right_nappinfos,
right_appinfos);
sjinfo->syn_lefthand = adjust_child_relids(sjinfo->syn_lefthand,
left_nappinfos, left_appinfos);
sjinfo->syn_righthand = adjust_child_relids(sjinfo->syn_righthand,
right_nappinfos,
right_appinfos);
sjinfo->semi_rhs_exprs = (List *) adjust_appendrel_attrs(root,
(Node *) sjinfo->semi_rhs_exprs,
right_nappinfos,
right_appinfos);
pfree(left_appinfos);
pfree(right_appinfos);
return sjinfo;
}
/*
* find_appinfos_by_relids
* Find AppendRelInfo structures for all relations specified by relids.
*
* The AppendRelInfos are returned in an array, which can be pfree'd by the
* caller. *nappinfos is set to the the number of entries in the array.
*/
AppendRelInfo **
find_appinfos_by_relids(PlannerInfo *root, Relids relids, int *nappinfos)
{
ListCell *lc;
AppendRelInfo **appinfos;
int cnt = 0;
*nappinfos = bms_num_members(relids);
appinfos = (AppendRelInfo **) palloc(sizeof(AppendRelInfo *) * *nappinfos);
foreach(lc, root->append_rel_list)
{
AppendRelInfo *appinfo = lfirst(lc);
if (bms_is_member(appinfo->child_relid, relids))
{
appinfos[cnt] = appinfo;
cnt++;
/* Stop when we have gathered all the AppendRelInfos. */
if (cnt == *nappinfos)
return appinfos;
}
}
/* Should have found the entries ... */
elog(ERROR, "did not find all requested child rels in append_rel_list");
return NULL; /* not reached */
}
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