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Support deferrable uniqueness constraints.
The current implementation fires an AFTER ROW trigger for each tuple that looks like it might be non-unique according to the index contents at the time of insertion. This works well as long as there aren't many conflicts, but won't scale to massive unique-key reassignments. Improving that case is a TODO item. Dean Rasheed
This commit is contained in:
Tom Lane
@ -19,7 +19,7 @@
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* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/backend/parser/parse_utilcmd.c,v 2.23 2009/07/16 06:33:43 petere Exp $
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* $PostgreSQL: pgsql/src/backend/parser/parse_utilcmd.c,v 2.24 2009/07/29 20:56:19 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -33,6 +33,7 @@
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#include "catalog/heap.h"
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#include "catalog/index.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_constraint.h"
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#include "catalog/pg_opclass.h"
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#include "catalog/pg_type.h"
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#include "commands/defrem.h"
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@ -801,15 +802,38 @@ generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
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/*
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* If the index is marked PRIMARY, it's certainly from a constraint; else,
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* if it's not marked UNIQUE, it certainly isn't; else, we have to search
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* pg_depend to see if there's an associated unique constraint.
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* if it's not marked UNIQUE, it certainly isn't. If it is or might be
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* from a constraint, we have to fetch the constraint to check for
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* deferrability attributes.
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*/
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if (index->primary)
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index->isconstraint = true;
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else if (!index->unique)
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index->isconstraint = false;
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if (index->primary || index->unique)
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{
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Oid constraintId = get_index_constraint(source_relid);
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if (OidIsValid(constraintId))
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{
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HeapTuple ht_constr;
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Form_pg_constraint conrec;
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ht_constr = SearchSysCache(CONSTROID,
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ObjectIdGetDatum(constraintId),
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0, 0, 0);
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if (!HeapTupleIsValid(ht_constr))
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elog(ERROR, "cache lookup failed for constraint %u",
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constraintId);
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conrec = (Form_pg_constraint) GETSTRUCT(ht_constr);
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index->isconstraint = true;
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index->deferrable = conrec->condeferrable;
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index->initdeferred = conrec->condeferred;
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ReleaseSysCache(ht_constr);
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}
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else
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index->isconstraint = false;
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}
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else
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index->isconstraint = OidIsValid(get_index_constraint(source_relid));
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index->isconstraint = false;
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/* Get the index expressions, if any */
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datum = SysCacheGetAttr(INDEXRELID, ht_idx,
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@ -1039,7 +1063,9 @@ transformIndexConstraints(ParseState *pstate, CreateStmtContext *cxt)
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if (equal(index->indexParams, priorindex->indexParams) &&
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equal(index->whereClause, priorindex->whereClause) &&
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strcmp(index->accessMethod, priorindex->accessMethod) == 0)
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strcmp(index->accessMethod, priorindex->accessMethod) == 0 &&
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index->deferrable == priorindex->deferrable &&
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index->initdeferred == priorindex->initdeferred)
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{
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priorindex->unique |= index->unique;
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@ -1092,6 +1118,8 @@ transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
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*/
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}
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index->isconstraint = true;
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index->deferrable = constraint->deferrable;
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index->initdeferred = constraint->initdeferred;
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if (constraint->name != NULL)
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index->idxname = pstrdup(constraint->name);
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@ -1853,8 +1881,9 @@ transformAlterTableStmt(AlterTableStmt *stmt, const char *queryString)
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* to attach constraint attributes to their primary constraint nodes
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* and detect inconsistent/misplaced constraint attributes.
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*
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* NOTE: currently, attributes are only supported for FOREIGN KEY primary
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* constraints, but someday they ought to be supported for other constraints.
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* NOTE: currently, attributes are only supported for FOREIGN KEY, UNIQUE,
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* and PRIMARY KEY constraints, but someday they ought to be supported
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* for other constraint types.
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*/
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static void
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transformConstraintAttrs(List *constraintList)
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@ -1864,6 +1893,13 @@ transformConstraintAttrs(List *constraintList)
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bool saw_initially = false;
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ListCell *clist;
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#define SUPPORTS_ATTRS(node) \
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((node) != NULL && \
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(IsA((node), FkConstraint) || \
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(IsA((node), Constraint) && \
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(((Constraint *) (node))->contype == CONSTR_PRIMARY || \
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((Constraint *) (node))->contype == CONSTR_UNIQUE))))
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foreach(clist, constraintList)
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{
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Node *node = lfirst(clist);
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@ -1882,8 +1918,7 @@ transformConstraintAttrs(List *constraintList)
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switch (con->contype)
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{
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case CONSTR_ATTR_DEFERRABLE:
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if (lastprimarynode == NULL ||
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!IsA(lastprimarynode, FkConstraint))
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if (!SUPPORTS_ATTRS(lastprimarynode))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("misplaced DEFERRABLE clause")));
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@ -1892,11 +1927,14 @@ transformConstraintAttrs(List *constraintList)
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed")));
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saw_deferrability = true;
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((FkConstraint *) lastprimarynode)->deferrable = true;
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if (IsA(lastprimarynode, FkConstraint))
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((FkConstraint *) lastprimarynode)->deferrable = true;
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else
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((Constraint *) lastprimarynode)->deferrable = true;
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break;
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case CONSTR_ATTR_NOT_DEFERRABLE:
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if (lastprimarynode == NULL ||
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!IsA(lastprimarynode, FkConstraint))
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if (!SUPPORTS_ATTRS(lastprimarynode))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("misplaced NOT DEFERRABLE clause")));
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@ -1905,16 +1943,28 @@ transformConstraintAttrs(List *constraintList)
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed")));
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saw_deferrability = true;
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((FkConstraint *) lastprimarynode)->deferrable = false;
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if (saw_initially &&
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((FkConstraint *) lastprimarynode)->initdeferred)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
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if (IsA(lastprimarynode, FkConstraint))
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{
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((FkConstraint *) lastprimarynode)->deferrable = false;
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if (saw_initially &&
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((FkConstraint *) lastprimarynode)->initdeferred)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
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}
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else
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{
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((Constraint *) lastprimarynode)->deferrable = false;
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if (saw_initially &&
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((Constraint *) lastprimarynode)->initdeferred)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
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}
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break;
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case CONSTR_ATTR_DEFERRED:
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if (lastprimarynode == NULL ||
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!IsA(lastprimarynode, FkConstraint))
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if (!SUPPORTS_ATTRS(lastprimarynode))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("misplaced INITIALLY DEFERRED clause")));
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@ -1923,21 +1973,36 @@ transformConstraintAttrs(List *constraintList)
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed")));
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saw_initially = true;
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((FkConstraint *) lastprimarynode)->initdeferred = true;
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/*
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* If only INITIALLY DEFERRED appears, assume DEFERRABLE
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*/
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if (!saw_deferrability)
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((FkConstraint *) lastprimarynode)->deferrable = true;
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else if (!((FkConstraint *) lastprimarynode)->deferrable)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
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if (IsA(lastprimarynode, FkConstraint))
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{
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((FkConstraint *) lastprimarynode)->initdeferred = true;
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if (!saw_deferrability)
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((FkConstraint *) lastprimarynode)->deferrable = true;
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else if (!((FkConstraint *) lastprimarynode)->deferrable)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
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}
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else
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{
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((Constraint *) lastprimarynode)->initdeferred = true;
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if (!saw_deferrability)
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((Constraint *) lastprimarynode)->deferrable = true;
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else if (!((Constraint *) lastprimarynode)->deferrable)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
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}
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break;
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case CONSTR_ATTR_IMMEDIATE:
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if (lastprimarynode == NULL ||
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!IsA(lastprimarynode, FkConstraint))
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if (!SUPPORTS_ATTRS(lastprimarynode))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("misplaced INITIALLY IMMEDIATE clause")));
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@ -1946,8 +2011,12 @@ transformConstraintAttrs(List *constraintList)
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed")));
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saw_initially = true;
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((FkConstraint *) lastprimarynode)->initdeferred = false;
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if (IsA(lastprimarynode, FkConstraint))
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((FkConstraint *) lastprimarynode)->initdeferred = false;
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else
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((Constraint *) lastprimarynode)->initdeferred = false;
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break;
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default:
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/* Otherwise it's not an attribute */
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lastprimarynode = node;
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