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Commite84bf65

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committed
Ensure an index that uses a whole-row Var still depends on its table.
We failed to record any dependency on the underlying table for an indexdeclared like "create index i on t (foo(t.*))". This would create troubleif the table were dropped without previously dropping the index. To fix,simplify some overly-cute code in index_create(), accepting the possibilitythat sometimes the whole-table dependency will be redundant. Also documentthis hazard in dependency.c. Per report from Kevin Grittner.In passing, prevent a core dump in pg_get_indexdef() if the index's tablecan't be found. I came across this while experimenting with Kevin'sexample. Not sure it's a real issue when the catalogs aren't corrupt, butmight as well be cautious.Back-patch to all supported versions.
1 parent77459eb commite84bf65

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3 files changed

+40
-14
lines changed

3 files changed

+40
-14
lines changed

‎src/backend/catalog/dependency.c

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1235,6 +1235,12 @@ recordDependencyOnExpr(const ObjectAddress *depender,
12351235
* range table. An additional frammish is that dependencies on that
12361236
* relation (or its component columns) will be marked with 'self_behavior',
12371237
* whereas 'behavior' is used for everything else.
1238+
*
1239+
* NOTE: the caller should ensure that a whole-table dependency on the
1240+
* specified relation is created separately, if one is needed. In particular,
1241+
* a whole-row Var "relation.*" will not cause this routine to emit any
1242+
* dependency item. This is appropriate behavior for subexpressions of an
1243+
* ordinary query, so other cases need to cope as necessary.
12381244
*/
12391245
void
12401246
recordDependencyOnSingleRelExpr(constObjectAddress*depender,
@@ -1347,7 +1353,14 @@ find_expr_references_walker(Node *node,
13471353

13481354
/*
13491355
* A whole-row Var references no specific columns, so adds no new
1350-
* dependency.
1356+
* dependency. (We assume that there is a whole-table dependency
1357+
* arising from each underlying rangetable entry. While we could
1358+
* record such a dependency when finding a whole-row Var that
1359+
* references a relation directly, it's quite unclear how to extend
1360+
* that to whole-row Vars for JOINs, so it seems better to leave the
1361+
* responsibility with the range table. Note that this poses some
1362+
* risks for identifying dependencies of stand-alone expressions:
1363+
* whole-table references may need to be created separately.)
13511364
*/
13521365
if (var->varattno==InvalidAttrNumber)
13531366
return false;

‎src/backend/catalog/index.c

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -50,7 +50,6 @@
5050
#include"nodes/makefuncs.h"
5151
#include"nodes/nodeFuncs.h"
5252
#include"optimizer/clauses.h"
53-
#include"optimizer/var.h"
5453
#include"parser/parser.h"
5554
#include"storage/bufmgr.h"
5655
#include"storage/lmgr.h"
@@ -853,16 +852,12 @@ index_create(Oid heapRelationId,
853852
}
854853

855854
/*
856-
* It's possible for an index to not depend on any columns of the
857-
* table at all, in which case we need to give it a dependency on
858-
* the table as a whole; else it won't get dropped when the table
859-
* is dropped.This edge case is not totally useless; for
860-
* example, a unique index on a constant expression can serve to
861-
* prevent a table from containing more than one row.
855+
* If there are no simply-referenced columns, give the index an
856+
* auto dependency on the whole table. In most cases, this will
857+
* be redundant, but it might not be if the index expressions and
858+
* predicate contain no Vars or only whole-row Vars.
862859
*/
863-
if (!have_simple_col&&
864-
!contain_vars_of_level((Node*)indexInfo->ii_Expressions,0)&&
865-
!contain_vars_of_level((Node*)indexInfo->ii_Predicate,0))
860+
if (!have_simple_col)
866861
{
867862
referenced.classId=RelationRelationId;
868863
referenced.objectId=heapRelationId;

‎src/backend/utils/adt/ruleutils.c

Lines changed: 21 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -219,6 +219,7 @@ static void get_opclass_name(Oid opclass, Oid actual_datatype,
219219
staticNode*processIndirection(Node*node,deparse_context*context,
220220
boolprintit);
221221
staticvoidprintSubscripts(ArrayRef*aref,deparse_context*context);
222+
staticchar*get_relation_name(Oidrelid);
222223
staticchar*generate_relation_name(Oidrelid,List*namespaces);
223224
staticchar*generate_function_name(Oidfuncid,intnargs,List*argnames,
224225
Oid*argtypes,bool*is_variadic);
@@ -832,7 +833,7 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
832833

833834
indexpr_item=list_head(indexprs);
834835

835-
context=deparse_context_for(get_rel_name(indrelid),indrelid);
836+
context=deparse_context_for(get_relation_name(indrelid),indrelid);
836837

837838
/*
838839
* Start the index definition.Note that the index's name should never be
@@ -1236,7 +1237,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
12361237
if (conForm->conrelid!=InvalidOid)
12371238
{
12381239
/* relation constraint */
1239-
context=deparse_context_for(get_rel_name(conForm->conrelid),
1240+
context=deparse_context_for(get_relation_name(conForm->conrelid),
12401241
conForm->conrelid);
12411242
}
12421243
else
@@ -6074,7 +6075,7 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
60746075
gavealias= true;
60756076
}
60766077
elseif (rte->rtekind==RTE_RELATION&&
6077-
strcmp(rte->eref->aliasname,get_rel_name(rte->relid))!=0)
6078+
strcmp(rte->eref->aliasname,get_relation_name(rte->relid))!=0)
60786079
{
60796080
/*
60806081
* Apparently the rel has been renamed since the rule was made.
@@ -6574,6 +6575,23 @@ quote_qualified_identifier(const char *qualifier,
65746575
returnbuf.data;
65756576
}
65766577

6578+
/*
6579+
* get_relation_name
6580+
*Get the unqualified name of a relation specified by OID
6581+
*
6582+
* This differs from the underlying get_rel_name() function in that it will
6583+
* throw error instead of silently returning NULL if the OID is bad.
6584+
*/
6585+
staticchar*
6586+
get_relation_name(Oidrelid)
6587+
{
6588+
char*relname=get_rel_name(relid);
6589+
6590+
if (!relname)
6591+
elog(ERROR,"cache lookup failed for relation %u",relid);
6592+
returnrelname;
6593+
}
6594+
65776595
/*
65786596
* generate_relation_name
65796597
*Compute the name to display for a relation specified by OID

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