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postgres/src/backend/optimizer/prep/prepunion.c
Andres Freund 2cd7084524 Change tupledesc->attrs[n] to TupleDescAttr(tupledesc, n). 
This is a mechanical change in preparation for a later commit that
will change the layout of TupleDesc.  Introducing a macro to abstract
the details of where attributes are stored will allow us to change
that in separate step and revise it in future.

Author: Thomas Munro, editorialized by Andres Freund
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com
2017-08-20 11:19:07 -07:00

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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/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 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, NULL, 0, NIL);
/* 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, NULL, 0, NIL);
/* 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);
/* punt if nothing to group on (can this happen?) */
if (groupList == NIL)
return path;
/*
* 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 (!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);
/* punt if nothing to group on (can this happen?) */
if (groupList == NIL)
return path;
/*
* 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 */
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,
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,
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; there is no
* need to scan them since they can't have 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;
List *appinfos;
ListCell *l;
bool has_child;
PartitionedChildRelInfo *pcinfo;
List *partitioned_child_rels = NIL;
/* 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 */
appinfos = NIL;
has_child = false;
foreach(l, inhOIDs)
{
Oid childOID = lfirst_oid(l);
Relation newrelation;
RangeTblEntry *childrte;
Index childRTindex;
AppendRelInfo *appinfo;
/* 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;
}
/*
* 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(rte);
childrte->relid = childOID;
childrte->relkind = newrelation->rd_rel->relkind;
childrte->inh = false;
childrte->requiredPerms = 0;
childrte->securityQuals = NIL;
parse->rtable = lappend(parse->rtable, childrte);
childRTindex = list_length(parse->rtable);
/*
* Build an AppendRelInfo for this parent and child, unless the child
* is a partitioned table.
*/
if (childrte->relkind != RELKIND_PARTITIONED_TABLE)
{
/* Remember if we saw a real child. */
if (childOID != parentOID)
has_child = true;
appinfo = makeNode(AppendRelInfo);
appinfo->parent_relid = rti;
appinfo->child_relid = childRTindex;
appinfo->parent_reltype = oldrelation->rd_rel->reltype;
appinfo->child_reltype = newrelation->rd_rel->reltype;
make_inh_translation_list(oldrelation, newrelation, 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(rte->selectedCols,
appinfo->translated_vars);
childrte->insertedCols = translate_col_privs(rte->insertedCols,
appinfo->translated_vars);
childrte->updatedCols = translate_col_privs(rte->updatedCols,
appinfo->translated_vars);
}
}
else
partitioned_child_rels = lappend_int(partitioned_child_rels,
childRTindex);
/*
* Build a PlanRowMark if parent is marked FOR UPDATE/SHARE.
*/
if (oldrc)
{
PlanRowMark *newrc = makeNode(PlanRowMark);
newrc->rti = childRTindex;
newrc->prti = rti;
newrc->rowmarkId = oldrc->rowmarkId;
/* Reselect rowmark type, because relkind might not match parent */
newrc->markType = select_rowmark_type(childrte, oldrc->strength);
newrc->allMarkTypes = (1 << newrc->markType);
newrc->strength = oldrc->strength;
newrc->waitPolicy = oldrc->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).
*/
newrc->isParent = (childrte->relkind == RELKIND_PARTITIONED_TABLE);
/* Include child's rowmark type in parent's allMarkTypes */
oldrc->allMarkTypes |= newrc->allMarkTypes;
root->rowMarks = lappend(root->rowMarks, newrc);
}
/* Close child relations, but keep locks */
if (childOID != parentOID)
heap_close(newrelation, NoLock);
}
heap_close(oldrelation, NoLock);
/*
* If all the children were temp tables or a partitioned parent did not
* have any leaf partitions, 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 (!has_child)
{
/* Clear flag before returning */
rte->inh = false;
return;
}
/*
* We keep a list of objects in root, each of which maps a partitioned
* parent RT index to the list of RT indexes of its 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 (partitioned_child_rels != NIL)
{
pcinfo = makeNode(PartitionedChildRelInfo);
Assert(rte->relkind == RELKIND_PARTITIONED_TABLE);
pcinfo->parent_relid = rti;
pcinfo->child_rels = partitioned_child_rels;
root->pcinfo_list = lappend(root->pcinfo_list, pcinfo);
}
/* Otherwise, OK to add to root->append_rel_list */
root->append_rel_list = list_concat(root->append_rel_list, appinfos);
}
/*
* 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;
}
/*
* 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;
}
/*
* 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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