From 5d7684425ba993371a4fe1608ffdc39be27be666 Mon Sep 17 00:00:00 2001 From: "okbob@github.com" Date: Mon, 4 Apr 2022 20:32:45 +0200 Subject: [PATCH 04/10] support of LET command in PLpgSQL The support for LET command as PLpgSQL command does assigning of expression evaluation to session variable. With extra support in PLpgSQL we can implement SQL LET command like usual PostgreSQL's command (and the assigning of result to session variable is not side effect of query evaluation). --- src/backend/executor/spi.c | 3 ++ src/backend/parser/gram.y | 8 ++++ src/backend/parser/parser.c | 3 +- src/include/parser/parser.h | 6 ++- src/pl/plpgsql/src/pl_exec.c | 55 +++++++++++++++++++++++++ src/pl/plpgsql/src/pl_funcs.c | 24 +++++++++++ src/pl/plpgsql/src/pl_gram.y | 28 ++++++++++++- src/pl/plpgsql/src/pl_reserved_kwlist.h | 1 + src/pl/plpgsql/src/plpgsql.h | 14 ++++++- src/tools/pgindent/typedefs.list | 1 + 10 files changed, 139 insertions(+), 4 deletions(-) diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c index 256632c985..f11df000e7 100644 --- a/src/backend/executor/spi.c +++ b/src/backend/executor/spi.c @@ -2967,6 +2967,9 @@ _SPI_error_callback(void *arg) case RAW_PARSE_PLPGSQL_ASSIGN3: errcontext("PL/pgSQL assignment \"%s\"", query); break; + case RAW_PARSE_PLPGSQL_LET: + errcontext("LET statement \"%s\"", query); + break; default: errcontext("SQL statement \"%s\"", query); break; diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index 8ad66520bb..3c6faa42a6 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -814,6 +814,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query); %token MODE_PLPGSQL_ASSIGN1 %token MODE_PLPGSQL_ASSIGN2 %token MODE_PLPGSQL_ASSIGN3 +%token MODE_PLPGSQL_LET /* Precedence: lowest to highest */ @@ -929,6 +930,13 @@ parse_toplevel: pg_yyget_extra(yyscanner)->parsetree = list_make1(makeRawStmt((Node *) n, 0)); } + | MODE_PLPGSQL_LET LetStmt + { + LetStmt *n = (LetStmt *) $2; + n->plpgsql_mode = true; + pg_yyget_extra(yyscanner)->parsetree = + list_make1(makeRawStmt((Node *) n, 0)); + } ; /* diff --git a/src/backend/parser/parser.c b/src/backend/parser/parser.c index e17c310cc1..d58f06342a 100644 --- a/src/backend/parser/parser.c +++ b/src/backend/parser/parser.c @@ -61,7 +61,8 @@ raw_parser(const char *str, RawParseMode mode) MODE_PLPGSQL_EXPR, /* RAW_PARSE_PLPGSQL_EXPR */ MODE_PLPGSQL_ASSIGN1, /* RAW_PARSE_PLPGSQL_ASSIGN1 */ MODE_PLPGSQL_ASSIGN2, /* RAW_PARSE_PLPGSQL_ASSIGN2 */ - MODE_PLPGSQL_ASSIGN3 /* RAW_PARSE_PLPGSQL_ASSIGN3 */ + MODE_PLPGSQL_ASSIGN3, /* RAW_PARSE_PLPGSQL_ASSIGN3 */ + MODE_PLPGSQL_LET /* RAW_PARSE_PLPGSQL_LET */ }; yyextra.have_lookahead = true; diff --git a/src/include/parser/parser.h b/src/include/parser/parser.h index 8d90064d87..0548ad8370 100644 --- a/src/include/parser/parser.h +++ b/src/include/parser/parser.h @@ -33,6 +33,9 @@ * RAW_PARSE_PLPGSQL_ASSIGNn: parse a PL/pgSQL assignment statement, * and return a one-element List containing a RawStmt node. "n" * gives the number of dotted names comprising the target ColumnRef. + * + * RAW_PARSE_PLPGSQL_LET: parse a LET statement, and return a + * one-element List containing a RawStmt node. */ typedef enum { @@ -41,7 +44,8 @@ typedef enum RAW_PARSE_PLPGSQL_EXPR, RAW_PARSE_PLPGSQL_ASSIGN1, RAW_PARSE_PLPGSQL_ASSIGN2, - RAW_PARSE_PLPGSQL_ASSIGN3 + RAW_PARSE_PLPGSQL_ASSIGN3, + RAW_PARSE_PLPGSQL_LET } RawParseMode; /* Values for the backslash_quote GUC */ diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c index 4b76f7699a..583f84e8ea 100644 --- a/src/pl/plpgsql/src/pl_exec.c +++ b/src/pl/plpgsql/src/pl_exec.c @@ -24,6 +24,7 @@ #include "catalog/pg_proc.h" #include "catalog/pg_type.h" #include "commands/defrem.h" +#include "commands/session_variable.h" #include "executor/execExpr.h" #include "executor/spi.h" #include "executor/tstoreReceiver.h" @@ -328,6 +329,8 @@ static int exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt); static int exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt); +static int exec_stmt_let(PLpgSQL_execstate *estate, + PLpgSQL_stmt_let *let); static void plpgsql_estate_setup(PLpgSQL_execstate *estate, PLpgSQL_function *func, @@ -2119,6 +2122,10 @@ exec_stmts(PLpgSQL_execstate *estate, List *stmts) rc = exec_stmt_rollback(estate, (PLpgSQL_stmt_rollback *) stmt); break; + case PLPGSQL_STMT_LET: + rc = exec_stmt_let(estate, (PLpgSQL_stmt_let *) stmt); + break; + default: /* point err_stmt to parent, since this one seems corrupt */ estate->err_stmt = save_estmt; @@ -4998,6 +5005,54 @@ exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt) return PLPGSQL_RC_OK; } +/* ---------- + * exec_stmt_let Evaluate an expression and + * put the result into a session variable. + * ---------- + */ +static int +exec_stmt_let(PLpgSQL_execstate *estate, PLpgSQL_stmt_let *stmt) +{ + bool isNull; + Oid valtype; + int32 valtypmod; + Datum value; + Oid varid; + + List *plansources; + CachedPlanSource *plansource; + + value = exec_eval_expr(estate, + stmt->expr, + &isNull, + &valtype, + &valtypmod); + + /* + * Oid of target session variable is stored in Query structure. It is + * safer to read this value directly from the plan than to hold this value + * in the plpgsql context, because it's not necessary to handle + * invalidation of the cached value. Next operations are read only without + * any allocations, so we can expect that retrieving varid from Query + * should be fast. + */ + plansources = SPI_plan_get_plan_sources(stmt->expr->plan); + if (list_length(plansources) != 1) + elog(ERROR, "unexpected length of plansources of query for LET statement"); + + plansource = (CachedPlanSource *) linitial(plansources); + if (list_length(plansource->query_list) != 1) + elog(ERROR, "unexpected length of plansource of query for LET statement"); + + varid = linitial_node(Query, plansource->query_list)->resultVariable; + if (!OidIsValid(varid)) + elog(ERROR, "oid of target session variable is not valid"); + + SetSessionVariableWithSecurityCheck(varid, value, isNull); + + return PLPGSQL_RC_OK; +} + /* ---------- * exec_assign_expr Put an expression's result into a variable. * ---------- diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c index f010515fdf..73142a9147 100644 --- a/src/pl/plpgsql/src/pl_funcs.c +++ b/src/pl/plpgsql/src/pl_funcs.c @@ -288,6 +288,8 @@ plpgsql_stmt_typename(PLpgSQL_stmt *stmt) return "COMMIT"; case PLPGSQL_STMT_ROLLBACK: return "ROLLBACK"; + case PLPGSQL_STMT_LET: + return "LET"; } return "unknown"; @@ -370,6 +372,7 @@ static void free_perform(PLpgSQL_stmt_perform *stmt); static void free_call(PLpgSQL_stmt_call *stmt); static void free_commit(PLpgSQL_stmt_commit *stmt); static void free_rollback(PLpgSQL_stmt_rollback *stmt); +static void free_let(PLpgSQL_stmt_let *stmt); static void free_expr(PLpgSQL_expr *expr); @@ -459,6 +462,9 @@ free_stmt(PLpgSQL_stmt *stmt) case PLPGSQL_STMT_ROLLBACK: free_rollback((PLpgSQL_stmt_rollback *) stmt); break; + case PLPGSQL_STMT_LET: + free_let((PLpgSQL_stmt_let *) stmt); + break; default: elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type); break; @@ -713,6 +719,12 @@ free_getdiag(PLpgSQL_stmt_getdiag *stmt) { } +static void +free_let(PLpgSQL_stmt_let *stmt) +{ + free_expr(stmt->expr); +} + static void free_expr(PLpgSQL_expr *expr) { @@ -815,6 +827,7 @@ static void dump_perform(PLpgSQL_stmt_perform *stmt); static void dump_call(PLpgSQL_stmt_call *stmt); static void dump_commit(PLpgSQL_stmt_commit *stmt); static void dump_rollback(PLpgSQL_stmt_rollback *stmt); +static void dump_let(PLpgSQL_stmt_let *stmt); static void dump_expr(PLpgSQL_expr *expr); @@ -914,6 +927,9 @@ dump_stmt(PLpgSQL_stmt *stmt) case PLPGSQL_STMT_ROLLBACK: dump_rollback((PLpgSQL_stmt_rollback *) stmt); break; + case PLPGSQL_STMT_LET: + dump_let((PLpgSQL_stmt_let *) stmt); + break; default: elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type); break; @@ -1590,6 +1606,14 @@ dump_getdiag(PLpgSQL_stmt_getdiag *stmt) printf("\n"); } +static void +dump_let(PLpgSQL_stmt_let *stmt) +{ + dump_ind(); + dump_expr(stmt->expr); + printf("\n"); +} + static void dump_expr(PLpgSQL_expr *expr) { diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y index 6a09bfdd67..8aa6b5d7ab 100644 --- a/src/pl/plpgsql/src/pl_gram.y +++ b/src/pl/plpgsql/src/pl_gram.y @@ -195,7 +195,7 @@ static void check_raise_parameters(PLpgSQL_stmt_raise *stmt); %type stmt_return stmt_raise stmt_assert stmt_execsql %type stmt_dynexecute stmt_for stmt_perform stmt_call stmt_getdiag %type stmt_open stmt_fetch stmt_move stmt_close stmt_null -%type stmt_commit stmt_rollback +%type stmt_commit stmt_rollback stmt_let %type stmt_case stmt_foreach_a %type proc_exceptions @@ -302,6 +302,7 @@ static void check_raise_parameters(PLpgSQL_stmt_raise *stmt); %token K_INTO %token K_IS %token K_LAST +%token K_LET %token K_LOG %token K_LOOP %token K_MERGE @@ -870,6 +871,8 @@ proc_stmt : pl_block ';' { $$ = $1; } | stmt_rollback { $$ = $1; } + | stmt_let + { $$ = $1; } ; stmt_perform : K_PERFORM @@ -986,6 +989,29 @@ stmt_assign : T_DATUM } ; +stmt_let : K_LET + { + PLpgSQL_stmt_let *new; + RawParseMode pmode; + + pmode = RAW_PARSE_PLPGSQL_LET; + + new = palloc0(sizeof(PLpgSQL_stmt_let)); + new->cmd_type = PLPGSQL_STMT_LET; + new->lineno = plpgsql_location_to_lineno(@1); + new->stmtid = ++plpgsql_curr_compile->nstatements; + + /* Push back the head name to include it in the stmt */ + plpgsql_push_back_token(K_LET); + new->expr = read_sql_construct(';', 0, 0, ";", + pmode, + false, true, true, + NULL, NULL); + + $$ = (PLpgSQL_stmt *)new; + } + ; + stmt_getdiag : K_GET getdiag_area_opt K_DIAGNOSTICS getdiag_list ';' { PLpgSQL_stmt_getdiag *new; diff --git a/src/pl/plpgsql/src/pl_reserved_kwlist.h b/src/pl/plpgsql/src/pl_reserved_kwlist.h index c116abbb7a..90eb1ca8aa 100644 --- a/src/pl/plpgsql/src/pl_reserved_kwlist.h +++ b/src/pl/plpgsql/src/pl_reserved_kwlist.h @@ -40,6 +40,7 @@ PG_KEYWORD("from", K_FROM) PG_KEYWORD("if", K_IF) PG_KEYWORD("in", K_IN) PG_KEYWORD("into", K_INTO) +PG_KEYWORD("let", K_LET) PG_KEYWORD("loop", K_LOOP) PG_KEYWORD("not", K_NOT) PG_KEYWORD("null", K_NULL) diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h index 2b4bcd1dbe..22c9d78f30 100644 --- a/src/pl/plpgsql/src/plpgsql.h +++ b/src/pl/plpgsql/src/plpgsql.h @@ -127,7 +127,8 @@ typedef enum PLpgSQL_stmt_type PLPGSQL_STMT_PERFORM, PLPGSQL_STMT_CALL, PLPGSQL_STMT_COMMIT, - PLPGSQL_STMT_ROLLBACK + PLPGSQL_STMT_ROLLBACK, + PLPGSQL_STMT_LET } PLpgSQL_stmt_type; /* @@ -520,6 +521,17 @@ typedef struct PLpgSQL_stmt_assign PLpgSQL_expr *expr; } PLpgSQL_stmt_assign; +/* + * Let statement + */ +typedef struct PLpgSQL_stmt_let +{ + PLpgSQL_stmt_type cmd_type; + int lineno; + unsigned int stmtid; + PLpgSQL_expr *expr; +} PLpgSQL_stmt_let; + /* * PERFORM statement */ diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 5053ab081e..429fb8cdcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -1796,6 +1796,7 @@ PLpgSQL_stmt_forq PLpgSQL_stmt_fors PLpgSQL_stmt_getdiag PLpgSQL_stmt_if +PLpgSQL_stmt_let PLpgSQL_stmt_loop PLpgSQL_stmt_open PLpgSQL_stmt_perform -- 2.40.1