From aff7b8f4cd8e18791fb4140ddb8c93aa18f5b720 Mon Sep 17 00:00:00 2001 From: "okbob@github.com" Date: Thu, 4 Dec 2025 06:17:54 +0100 Subject: [PATCH 08/11] support CREATE IF NOT EXISTS and DROP IF EXISTS --- doc/src/sgml/ref/create_variable.sgml | 12 ++++- doc/src/sgml/ref/drop_variable.sgml | 12 ++++- src/backend/commands/session_variable.c | 46 +++++++++++++------ src/backend/parser/gram.y | 31 ++++++++++++- src/backend/tcop/utility.c | 2 +- src/include/commands/session_variable.h | 2 +- src/include/nodes/parsenodes.h | 4 +- .../expected/session_variables_ddl.out | 6 +++ .../regress/sql/session_variables_ddl.sql | 6 +++ 9 files changed, 100 insertions(+), 21 deletions(-) diff --git a/doc/src/sgml/ref/create_variable.sgml b/doc/src/sgml/ref/create_variable.sgml index 1315b1248c7..def368fc237 100644 --- a/doc/src/sgml/ref/create_variable.sgml +++ b/doc/src/sgml/ref/create_variable.sgml @@ -26,7 +26,7 @@ PostgreSQL documentation -CREATE { TEMP | TEMPORARY } VARIABLE name [ AS ] data_type +CREATE { TEMP | TEMPORARY } VARIABLE [ IF NOT EXISTS ] name [ AS ] data_type @@ -69,6 +69,16 @@ CREATE { TEMP | TEMPORARY } VARIABLE name + + IF NOT EXISTS + + + Do not throw an error if the name already exists. A notice is issued in + this case. + + + + name diff --git a/doc/src/sgml/ref/drop_variable.sgml b/doc/src/sgml/ref/drop_variable.sgml index dede42e4ffb..5de6a737493 100644 --- a/doc/src/sgml/ref/drop_variable.sgml +++ b/doc/src/sgml/ref/drop_variable.sgml @@ -26,7 +26,7 @@ PostgreSQL documentation -DROP VARIABLE name +DROP VARIABLE [ IF EXISTS ] name @@ -42,6 +42,16 @@ DROP VARIABLE name Parameters + + IF EXISTS + + + Do not throw an error if the session variable does not exist. A notice is + issued in this case. + + + + name diff --git a/src/backend/commands/session_variable.c b/src/backend/commands/session_variable.c index c75f851bad2..861a9317686 100644 --- a/src/backend/commands/session_variable.c +++ b/src/backend/commands/session_variable.c @@ -93,7 +93,7 @@ create_sessionvars_hashtables(void) * Returns entry of session variable specified by name */ static SVariable -search_variable(char *varname) +search_variable(char *varname, bool missing_ok) { SVariable svar; @@ -103,7 +103,7 @@ search_variable(char *varname) svar = (SVariable) hash_search(sessionvars, varname, HASH_FIND, NULL); - if (!svar) + if (!svar && !missing_ok) ereport(ERROR, (errcode(ERRCODE_UNDEFINED_OBJECT), errmsg("session variable \"%s\" doesn't exist", @@ -125,7 +125,7 @@ get_session_variable_type_typmod_collid(char *varname, { SVariable svar; - svar = search_variable(varname); + svar = search_variable(varname, false); /* only owner can set content of variable */ *typid = svar->vartype; @@ -145,7 +145,7 @@ GetSessionVariableWithTypecheck(char *varname, SVariable svar; Datum result; - svar = search_variable(varname); + svar = search_variable(varname, false); if (svar->vartype != typid || svar->vartypmod != typmod) ereport(ERROR, @@ -182,7 +182,7 @@ SetSessionVariableWithTypecheck(char *varname, { SVariable svar; - svar = search_variable(varname); + svar = search_variable(varname, false); if (svar->vartype != typid || svar->vartypmod != typmod) ereport(ERROR, @@ -278,10 +278,21 @@ CreateVariable(ParseState *pstate, CreateSessionVarStmt *stmt) HASH_ENTER, &found); if (found) - ereport(ERROR, - (errcode(ERRCODE_DUPLICATE_OBJECT), - errmsg("session variable \"%s\" already exists", - stmt->name))); + { + if (stmt->if_not_exists) + { + ereport(NOTICE, + (errcode(ERRCODE_DUPLICATE_OBJECT), + errmsg("session variable \"%s\" already exists, skipping", + stmt->name))); + return; + } + else + ereport(ERROR, + (errcode(ERRCODE_DUPLICATE_OBJECT), + errmsg("session variable \"%s\" already exists", + stmt->name))); + } namestrcpy(&svar->varname, stmt->name); svar->vartype = typeid; @@ -299,7 +310,7 @@ CreateVariable(ParseState *pstate, CreateSessionVarStmt *stmt) * Drop variable by name */ void -DropVariableByName(char *varname) +DropVariableByName(DropSessionVarStmt *stmt) { SVariable svar; @@ -311,20 +322,27 @@ DropVariableByName(char *varname) PreventCommandIfParallelMode("DROP VARIABLE"); PreventCommandDuringRecovery("DROP VARIABLE"); - svar = search_variable(varname); + svar = search_variable(stmt->name, stmt->missing_ok); + if (!svar) + { + ereport(NOTICE, + (errmsg("session variable \"%s\" does not exists, skipping", + stmt->name))); + return; + } /* only owner can get content of variable */ if (svar->varowner != GetUserId() && !superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("must be owner of session variable %s", - varname))); + stmt->name))); if (!svar->typbyval && !svar->isnull) pfree(DatumGetPointer(svar->value)); if (hash_search(sessionvars, - varname, + stmt->name, HASH_REMOVE, NULL) == NULL) elog(ERROR, "hash table corrupted"); @@ -348,7 +366,7 @@ ExecuteLetStmt(ParseState *pstate, char *varname = query->resultVariable; SVariable svar; - svar = search_variable(varname); + svar = search_variable(varname, false); /* only owner can set content of variable */ if (svar->varowner != GetUserId() && !superuser()) diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index 90821c62087..4257f1e0274 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -5448,7 +5448,7 @@ create_extension_opt_item: /***************************************************************************** * * QUERY : - * CREATE { TEMP | TEMPORARY } VARIABLE varname [AS] type + * CREATE { TEMP | TEMPORARY } VARIABLE [IF NOT EXISTS ] varname [AS] type * *****************************************************************************/ @@ -5465,14 +5465,31 @@ CreateSessionVarStmt: n->name = $4; n->typeName = $6; + n->if_not_exists = false; + $$ = (Node *) n; + } + | CREATE OptTemp VARIABLE IF_P NOT EXISTS ColId opt_as Typename + { + CreateSessionVarStmt *n = makeNode(CreateSessionVarStmt); + + if ($2 != RELPERSISTENCE_TEMP) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("only temporal session variables are supported"), + parser_errposition(@2))); + + n->name = $7; + n->typeName = $9; + n->if_not_exists = true; $$ = (Node *) n; } + ; /***************************************************************************** * * QUERY : - * DROP VARIABLE varname + * DROP VARIABLE [ IF EXISTS ] varname * *****************************************************************************/ @@ -5482,8 +5499,18 @@ DropSessionVarStmt: DropSessionVarStmt *n = makeNode(DropSessionVarStmt); n->name = $3; + n->missing_ok = false; + $$ = (Node *) n; + } + | DROP VARIABLE IF_P EXISTS ColId + { + DropSessionVarStmt *n = makeNode(DropSessionVarStmt); + + n->name = $5; + n->missing_ok = true; $$ = (Node *) n; } + ; /***************************************************************************** diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c index fda4e019b13..5c34a8e95a1 100644 --- a/src/backend/tcop/utility.c +++ b/src/backend/tcop/utility.c @@ -1076,7 +1076,7 @@ standard_ProcessUtility(PlannedStmt *pstmt, case T_DropSessionVarStmt: /* No event triggers for catalog less session variables */ - DropVariableByName(((DropSessionVarStmt *) parsetree)->name); + DropVariableByName((DropSessionVarStmt *) parsetree); break; case T_LetStmt: diff --git a/src/include/commands/session_variable.h b/src/include/commands/session_variable.h index cc1aa7ce23b..3f07ae55aac 100644 --- a/src/include/commands/session_variable.h +++ b/src/include/commands/session_variable.h @@ -22,7 +22,7 @@ #include "tcop/cmdtag.h" extern void CreateVariable(ParseState *pstate, CreateSessionVarStmt *stmt); -extern void DropVariableByName(char *varname); +extern void DropVariableByName(DropSessionVarStmt *stmt); extern Datum GetSessionVariableWithTypecheck(char *varname, Oid typid, int32 typmod, bool *isnull); extern void SetSessionVariableWithTypecheck(char *varname, diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 7d77a368b06..1efd0a22ad5 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -3701,6 +3701,7 @@ typedef struct CreateSessionVarStmt NodeTag type; char *name; /* the variable to create */ TypeName *typeName; /* the type of variable */ + bool if_not_exists; /* just do nothing if variable already exists? */ } CreateSessionVarStmt; /* ---------------------- @@ -3710,7 +3711,8 @@ typedef struct CreateSessionVarStmt typedef struct DropSessionVarStmt { NodeTag type; - char *name; + char *name; /* the variable name to drop */ + bool missing_ok; /* skip error of variable is missing */ } DropSessionVarStmt; diff --git a/src/test/regress/expected/session_variables_ddl.out b/src/test/regress/expected/session_variables_ddl.out index c36febd894e..9f5b088de72 100644 --- a/src/test/regress/expected/session_variables_ddl.out +++ b/src/test/regress/expected/session_variables_ddl.out @@ -48,3 +48,9 @@ ERROR: session variable "x" already exists DISCARD TEMP; -- should be ok CREATE TEMP VARIABLE x AS int; +-- should be ok +CREATE TEMP VARIABLE IF NOT EXISTS x AS int; +NOTICE: session variable "x" already exists, skipping +DROP VARIABLE x; +DROP VARIABLE IF EXISTS x; +NOTICE: session variable "x" does not exists, skipping diff --git a/src/test/regress/sql/session_variables_ddl.sql b/src/test/regress/sql/session_variables_ddl.sql index 7fd739d6677..60f78671e3b 100644 --- a/src/test/regress/sql/session_variables_ddl.sql +++ b/src/test/regress/sql/session_variables_ddl.sql @@ -64,3 +64,9 @@ DISCARD TEMP; -- should be ok CREATE TEMP VARIABLE x AS int; + +-- should be ok +CREATE TEMP VARIABLE IF NOT EXISTS x AS int; + +DROP VARIABLE x; +DROP VARIABLE IF EXISTS x; -- 2.53.0