From: Tom Lane Date: Tue, 2 Nov 2010 21:15:35 +0000 (-0400) Subject: Ensure an index that uses a whole-row Var still depends on its table. X-Git-Tag: REL8_1_23~19 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2868b0cbe061724b7d46234cf053f7fdb3672600;p=thirdparty%2Fpostgresql.git 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 index declared like "create index i on t (foo(t.*))". This would create trouble if the table were dropped without previously dropping the index. To fix, simplify some overly-cute code in index_create(), accepting the possibility that sometimes the whole-table dependency will be redundant. Also document this hazard in dependency.c. Per report from Kevin Grittner. In passing, prevent a core dump in pg_get_indexdef() if the index's table can't be found. I came across this while experimenting with Kevin's example. Not sure it's a real issue when the catalogs aren't corrupt, but might as well be cautious. Back-patch to all supported versions. --- diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c index 4839a5acb97..24a01088bac 100644 --- a/src/backend/catalog/dependency.c +++ b/src/backend/catalog/dependency.c @@ -890,6 +890,12 @@ recordDependencyOnExpr(const ObjectAddress *depender, * range table. An additional frammish is that dependencies on that * relation (or its component columns) will be marked with 'self_behavior', * whereas 'behavior' is used for everything else. + * + * NOTE: the caller should ensure that a whole-table dependency on the + * specified relation is created separately, if one is needed. In particular, + * a whole-row Var "relation.*" will not cause this routine to emit any + * dependency item. This is appropriate behavior for subexpressions of an + * ordinary query, so other cases need to cope as necessary. */ void recordDependencyOnSingleRelExpr(const ObjectAddress *depender, @@ -998,7 +1004,14 @@ find_expr_references_walker(Node *node, /* * A whole-row Var references no specific columns, so adds no new - * dependency. + * dependency. (We assume that there is a whole-table dependency + * arising from each underlying rangetable entry. While we could + * record such a dependency when finding a whole-row Var that + * references a relation directly, it's quite unclear how to extend + * that to whole-row Vars for JOINs, so it seems better to leave the + * responsibility with the range table. Note that this poses some + * risks for identifying dependencies of stand-alone expressions: + * whole-table references may need to be created separately.) */ if (var->varattno == InvalidAttrNumber) return false; diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 557dd82985d..d39b810f59b 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -39,7 +39,6 @@ #include "executor/executor.h" #include "miscadmin.h" #include "optimizer/clauses.h" -#include "optimizer/var.h" #include "parser/parse_expr.h" #include "storage/procarray.h" #include "storage/smgr.h" @@ -689,16 +688,12 @@ index_create(Oid heapRelationId, } /* - * It's possible for an index to not depend on any columns of - * the table at all, in which case we need to give it a dependency - * on the table as a whole; else it won't get dropped when the - * table is dropped. This edge case is not totally useless; - * for example, a unique index on a constant expression can serve - * to prevent a table from containing more than one row. + * If there are no simply-referenced columns, give the index an + * auto dependency on the whole table. In most cases, this will + * be redundant, but it might not be if the index expressions and + * predicate contain no Vars or only whole-row Vars. */ - if (!have_simple_col && - !contain_vars_of_level((Node *) indexInfo->ii_Expressions, 0) && - !contain_vars_of_level((Node *) indexInfo->ii_Predicate, 0)) + if (!have_simple_col) { referenced.classId = RelationRelationId; referenced.objectId = heapRelationId; diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index f1dd1d7dc5e..1f1ff503f9d 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -215,6 +215,7 @@ static void get_opclass_name(Oid opclass, Oid actual_datatype, StringInfo buf); static Node *processIndirection(Node *node, deparse_context *context); static void printSubscripts(ArrayRef *aref, deparse_context *context); +static char *get_relation_name(Oid relid); static char *generate_relation_name(Oid relid); static char *generate_function_name(Oid funcid, int nargs, Oid *argtypes); static char *generate_operator_name(Oid operid, Oid arg1, Oid arg2); @@ -721,7 +722,7 @@ pg_get_indexdef_worker(Oid indexrelid, int colno, bool showTblSpc, indexpr_item = list_head(indexprs); - context = deparse_context_for(get_rel_name(indrelid), indrelid); + context = deparse_context_for(get_relation_name(indrelid), indrelid); /* * Start the index definition. Note that the index's name should never be @@ -1092,7 +1093,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand, if (conForm->conrelid != InvalidOid) { /* relation constraint */ - context = deparse_context_for(get_rel_name(conForm->conrelid), + context = deparse_context_for(get_relation_name(conForm->conrelid), conForm->conrelid); } else @@ -4329,7 +4330,7 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context) gavealias = true; } else if (rte->rtekind == RTE_RELATION && - strcmp(rte->eref->aliasname, get_rel_name(rte->relid)) != 0) + strcmp(rte->eref->aliasname, get_relation_name(rte->relid)) != 0) { /* * Apparently the rel has been renamed since the rule was made. @@ -4840,6 +4841,23 @@ quote_qualified_identifier(const char *namespace, return buf.data; } +/* + * get_relation_name + * Get the unqualified name of a relation specified by OID + * + * This differs from the underlying get_rel_name() function in that it will + * throw error instead of silently returning NULL if the OID is bad. + */ +static char * +get_relation_name(Oid relid) +{ + char *relname = get_rel_name(relid); + + if (!relname) + elog(ERROR, "cache lookup failed for relation %u", relid); + return relname; +} + /* * generate_relation_name * Compute the name to display for a relation specified by OID