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Support writable foreign tables.

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This patch adds the core-system infrastructure needed to support updates
on foreign tables, and extends contrib/postgres_fdw to allow updates
against remote Postgres servers.  There's still a great deal of room for
improvement in optimization of remote updates, but at least there's basic
functionality there now.

KaiGai Kohei, reviewed by Alexander Korotkov and Laurenz Albe, and rather
heavily revised by Tom Lane.
This commit is contained in:
Tom Lane
2013-03-10 14:14:53 -04:00
parent 7f49a67f95
commit 21734d2fb8
29 changed files with 3672 additions and 347 deletions
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305
contrib/postgres_fdw/deparse.c
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@ -25,6 +25,7 @@
#include "postgres_fdw.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/transam.h"
@ -66,6 +67,14 @@ static bool is_builtin(Oid procid);
/*
* Functions to construct string representation of a node tree.
*/
static void deparseTargetList(StringInfo buf,
PlannerInfo *root,
Index rtindex,
Relation rel,
Bitmapset *attrs_used);
static void deparseReturningList(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *returningList);
static void deparseColumnRef(StringInfo buf, int varno, int varattno,
PlannerInfo *root);
static void deparseRelation(StringInfo buf, Oid relid);
@ -349,80 +358,104 @@ is_builtin(Oid oid)
/*
* Construct a simple SELECT statement that retrieves interesting columns
* Construct a simple SELECT statement that retrieves desired columns
* of the specified foreign table, and append it to "buf". The output
* contains just "SELECT ... FROM tablename".
*
* "Interesting" columns are those appearing in the rel's targetlist or
* in local_conds (conditions which can't be executed remotely).
*/
void
deparseSimpleSql(StringInfo buf,
deparseSelectSql(StringInfo buf,
PlannerInfo *root,
RelOptInfo *baserel,
List *local_conds)
Bitmapset *attrs_used)
{
RangeTblEntry *rte = root->simple_rte_array[baserel->relid];
Bitmapset *attrs_used = NULL;
RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
Relation rel;
/*
* Core code already has some lock on each rel being planned, so we can
* use NoLock here.
*/
rel = heap_open(rte->relid, NoLock);
/*
* Construct SELECT list
*/
appendStringInfoString(buf, "SELECT ");
deparseTargetList(buf, root, baserel->relid, rel, attrs_used);
/*
* Construct FROM clause
*/
appendStringInfoString(buf, " FROM ");
deparseRelation(buf, RelationGetRelid(rel));
heap_close(rel, NoLock);
}
/*
* Emit a target list that retrieves the columns specified in attrs_used.
* This is used for both SELECT and RETURNING targetlists.
*
* We list attributes in order of the foreign table's columns, but replace
* any attributes that need not be fetched with NULL constants. (We can't
* just omit such attributes, or we'll lose track of which columns are
* which at runtime.) Note however that any dropped columns are ignored.
* Also, if ctid needs to be retrieved, it's added at the end.
*/
static void
deparseTargetList(StringInfo buf,
PlannerInfo *root,
Index rtindex,
Relation rel,
Bitmapset *attrs_used)
{
TupleDesc tupdesc = RelationGetDescr(rel);
bool have_wholerow;
bool first;
AttrNumber attr;
ListCell *lc;
/* Collect all the attributes needed for joins or final output. */
pull_varattnos((Node *) baserel->reltargetlist, baserel->relid,
&attrs_used);
/* Add all the attributes used by local_conds. */
foreach(lc, local_conds)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
pull_varattnos((Node *) rinfo->clause, baserel->relid,
&attrs_used);
}
int i;
/* If there's a whole-row reference, we'll need all the columns. */
have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber,
attrs_used);
/*
* Construct SELECT list
*
* We list attributes in order of the foreign table's columns, but replace
* any attributes that need not be fetched with NULL constants. (We can't
* just omit such attributes, or we'll lose track of which columns are
* which at runtime.) Note however that any dropped columns are ignored.
*/
appendStringInfo(buf, "SELECT ");
first = true;
for (attr = 1; attr <= baserel->max_attr; attr++)
for (i = 1; i <= tupdesc->natts; i++)
{
Form_pg_attribute attr = tupdesc->attrs[i - 1];
/* Ignore dropped attributes. */
if (get_rte_attribute_is_dropped(rte, attr))
if (attr->attisdropped)
continue;
if (!first)
appendStringInfo(buf, ", ");
appendStringInfoString(buf, ", ");
first = false;
if (have_wholerow ||
bms_is_member(attr - FirstLowInvalidHeapAttributeNumber,
bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
attrs_used))
deparseColumnRef(buf, baserel->relid, attr, root);
deparseColumnRef(buf, rtindex, i, root);
else
appendStringInfo(buf, "NULL");
appendStringInfoString(buf, "NULL");
}
/*
* Add ctid if needed. We currently don't support retrieving any other
* system columns.
*/
if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber,
attrs_used))
{
if (!first)
appendStringInfoString(buf, ", ");
first = false;
appendStringInfoString(buf, "ctid");
}
/* Don't generate bad syntax if no undropped columns */
if (first)
appendStringInfo(buf, "NULL");
/*
* Construct FROM clause
*/
appendStringInfo(buf, " FROM ");
deparseRelation(buf, rte->relid);
appendStringInfoString(buf, "NULL");
}
/*
@ -432,9 +465,9 @@ deparseSimpleSql(StringInfo buf,
*/
void
appendWhereClause(StringInfo buf,
bool is_first,
PlannerInfo *root,
List *exprs,
PlannerInfo *root)
bool is_first)
{
ListCell *lc;
@ -444,9 +477,9 @@ appendWhereClause(StringInfo buf,
/* Connect expressions with "AND" and parenthesize each condition. */
if (is_first)
appendStringInfo(buf, " WHERE ");
appendStringInfoString(buf, " WHERE ");
else
appendStringInfo(buf, " AND ");
appendStringInfoString(buf, " AND ");
appendStringInfoChar(buf, '(');
deparseExpr(buf, ri->clause, root);
@ -456,6 +489,147 @@ appendWhereClause(StringInfo buf,
}
}
/*
* deparse remote INSERT statement
*/
void
deparseInsertSql(StringInfo buf, PlannerInfo *root, Index rtindex,
List *targetAttrs, List *returningList)
{
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
Relation rel = heap_open(rte->relid, NoLock);
TupleDesc tupdesc = RelationGetDescr(rel);
AttrNumber pindex;
bool first;
ListCell *lc;
appendStringInfoString(buf, "INSERT INTO ");
deparseRelation(buf, rte->relid);
appendStringInfoString(buf, "(");
first = true;
foreach(lc, targetAttrs)
{
int attnum = lfirst_int(lc);
Form_pg_attribute attr = tupdesc->attrs[attnum - 1];
Assert(!attr->attisdropped);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, root);
}
appendStringInfoString(buf, ") VALUES (");
pindex = 1;
first = true;
foreach(lc, targetAttrs)
{
if (!first)
appendStringInfoString(buf, ", ");
first = false;
appendStringInfo(buf, "$%d", pindex);
pindex++;
}
appendStringInfoString(buf, ")");
if (returningList)
deparseReturningList(buf, root, rtindex, rel, returningList);
heap_close(rel, NoLock);
}
/*
* deparse remote UPDATE statement
*/
void
deparseUpdateSql(StringInfo buf, PlannerInfo *root, Index rtindex,
List *targetAttrs, List *returningList)
{
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
Relation rel = heap_open(rte->relid, NoLock);
TupleDesc tupdesc = RelationGetDescr(rel);
AttrNumber pindex;
bool first;
ListCell *lc;
appendStringInfoString(buf, "UPDATE ");
deparseRelation(buf, rte->relid);
appendStringInfoString(buf, " SET ");
pindex = 2; /* ctid is always the first param */
first = true;
foreach(lc, targetAttrs)
{
int attnum = lfirst_int(lc);
Form_pg_attribute attr = tupdesc->attrs[attnum - 1];
Assert(!attr->attisdropped);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, root);
appendStringInfo(buf, " = $%d", pindex);
pindex++;
}
appendStringInfoString(buf, " WHERE ctid = $1");
if (returningList)
deparseReturningList(buf, root, rtindex, rel, returningList);
heap_close(rel, NoLock);
}
/*
* deparse remote DELETE statement
*/
void
deparseDeleteSql(StringInfo buf, PlannerInfo *root, Index rtindex,
List *returningList)
{
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
appendStringInfoString(buf, "DELETE FROM ");
deparseRelation(buf, rte->relid);
appendStringInfoString(buf, " WHERE ctid = $1");
if (returningList)
{
Relation rel = heap_open(rte->relid, NoLock);
deparseReturningList(buf, root, rtindex, rel, returningList);
heap_close(rel, NoLock);
}
}
/*
* deparse RETURNING clause of INSERT/UPDATE/DELETE
*/
static void
deparseReturningList(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *returningList)
{
Bitmapset *attrs_used;
/*
* We need the attrs mentioned in the query's RETURNING list.
*/
attrs_used = NULL;
pull_varattnos((Node *) returningList, rtindex,
&attrs_used);
appendStringInfoString(buf, " RETURNING ");
deparseTargetList(buf, root, rtindex, rel, attrs_used);
}
/*
* Construct SELECT statement to acquire size in blocks of given relation.
*
@ -495,13 +669,17 @@ deparseAnalyzeSql(StringInfo buf, Relation rel)
ListCell *lc;
bool first = true;
appendStringInfo(buf, "SELECT ");
appendStringInfoString(buf, "SELECT ");
for (i = 0; i < tupdesc->natts; i++)
{
/* Ignore dropped columns. */
if (tupdesc->attrs[i]->attisdropped)
continue;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
/* Use attribute name or column_name option. */
colname = NameStr(tupdesc->attrs[i]->attname);
options = GetForeignColumnOptions(relid, i + 1);
@ -517,20 +695,17 @@ deparseAnalyzeSql(StringInfo buf, Relation rel)
}
}
if (!first)
appendStringInfo(buf, ", ");
appendStringInfoString(buf, quote_identifier(colname));
first = false;
}
/* Don't generate bad syntax for zero-column relation. */
if (first)
appendStringInfo(buf, "NULL");
appendStringInfoString(buf, "NULL");
/*
* Construct FROM clause
*/
appendStringInfo(buf, " FROM ");
appendStringInfoString(buf, " FROM ");
deparseRelation(buf, relid);
}
@ -547,10 +722,10 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root)
ListCell *lc;
/* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
Assert(varno >= 1 && varno <= root->simple_rel_array_size);
Assert(!IS_SPECIAL_VARNO(varno));
/* Get RangeTblEntry from array in PlannerInfo. */
rte = root->simple_rte_array[varno];
rte = planner_rt_fetch(varno, root);
/*
* If it's a column of a foreign table, and it has the column_name FDW
@ -608,8 +783,8 @@ deparseRelation(StringInfo buf, Oid relid)
}
/*
* Note: we could skip printing the schema name if it's pg_catalog,
* but that doesn't seem worth the trouble.
* Note: we could skip printing the schema name if it's pg_catalog, but
* that doesn't seem worth the trouble.
*/
if (nspname == NULL)
nspname = get_namespace_name(get_rel_namespace(relid));
@ -1059,7 +1234,7 @@ deparseDistinctExpr(StringInfo buf, DistinctExpr *node, PlannerInfo *root)
appendStringInfoChar(buf, '(');
deparseExpr(buf, linitial(node->args), root);
appendStringInfo(buf, " IS DISTINCT FROM ");
appendStringInfoString(buf, " IS DISTINCT FROM ");
deparseExpr(buf, lsecond(node->args), root);
appendStringInfoChar(buf, ')');
}
@ -1146,7 +1321,7 @@ deparseBoolExpr(StringInfo buf, BoolExpr *node, PlannerInfo *root)
op = "OR";
break;
case NOT_EXPR:
appendStringInfo(buf, "(NOT ");
appendStringInfoString(buf, "(NOT ");
deparseExpr(buf, linitial(node->args), root);
appendStringInfoChar(buf, ')');
return;
@ -1173,9 +1348,9 @@ deparseNullTest(StringInfo buf, NullTest *node, PlannerInfo *root)
appendStringInfoChar(buf, '(');
deparseExpr(buf, node->arg, root);
if (node->nulltesttype == IS_NULL)
appendStringInfo(buf, " IS NULL)");
appendStringInfoString(buf, " IS NULL)");
else
appendStringInfo(buf, " IS NOT NULL)");
appendStringInfoString(buf, " IS NOT NULL)");
}
/*
@ -1187,11 +1362,11 @@ deparseArrayExpr(StringInfo buf, ArrayExpr *node, PlannerInfo *root)
bool first = true;
ListCell *lc;
appendStringInfo(buf, "ARRAY[");
appendStringInfoString(buf, "ARRAY[");
foreach(lc, node->elements)
{
if (!first)
appendStringInfo(buf, ", ");
appendStringInfoString(buf, ", ");
deparseExpr(buf, lfirst(lc), root);
first = false;
}