LCOV - code coverage report
Current view: top level - src/backend/commands - prepare.c (source / functions) Hit Total Coverage
Test: PostgreSQL 16beta1 Lines: 191 204 93.6 %
Date: 2023-05-30 18:12:27 Functions: 14 14 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * prepare.c
       4             :  *    Prepareable SQL statements via PREPARE, EXECUTE and DEALLOCATE
       5             :  *
       6             :  * This module also implements storage of prepared statements that are
       7             :  * accessed via the extended FE/BE query protocol.
       8             :  *
       9             :  *
      10             :  * Copyright (c) 2002-2023, PostgreSQL Global Development Group
      11             :  *
      12             :  * IDENTIFICATION
      13             :  *    src/backend/commands/prepare.c
      14             :  *
      15             :  *-------------------------------------------------------------------------
      16             :  */
      17             : #include "postgres.h"
      18             : 
      19             : #include <limits.h>
      20             : 
      21             : #include "access/xact.h"
      22             : #include "catalog/pg_type.h"
      23             : #include "commands/createas.h"
      24             : #include "commands/prepare.h"
      25             : #include "funcapi.h"
      26             : #include "miscadmin.h"
      27             : #include "nodes/nodeFuncs.h"
      28             : #include "parser/analyze.h"
      29             : #include "parser/parse_coerce.h"
      30             : #include "parser/parse_collate.h"
      31             : #include "parser/parse_expr.h"
      32             : #include "parser/parse_type.h"
      33             : #include "rewrite/rewriteHandler.h"
      34             : #include "tcop/pquery.h"
      35             : #include "tcop/utility.h"
      36             : #include "utils/builtins.h"
      37             : #include "utils/snapmgr.h"
      38             : #include "utils/timestamp.h"
      39             : 
      40             : 
      41             : /*
      42             :  * The hash table in which prepared queries are stored. This is
      43             :  * per-backend: query plans are not shared between backends.
      44             :  * The keys for this hash table are the arguments to PREPARE and EXECUTE
      45             :  * (statement names); the entries are PreparedStatement structs.
      46             :  */
      47             : static HTAB *prepared_queries = NULL;
      48             : 
      49             : static void InitQueryHashTable(void);
      50             : static ParamListInfo EvaluateParams(ParseState *pstate,
      51             :                                     PreparedStatement *pstmt, List *params,
      52             :                                     EState *estate);
      53             : static Datum build_regtype_array(Oid *param_types, int num_params);
      54             : 
      55             : /*
      56             :  * Implements the 'PREPARE' utility statement.
      57             :  */
      58             : void
      59        1576 : PrepareQuery(ParseState *pstate, PrepareStmt *stmt,
      60             :              int stmt_location, int stmt_len)
      61             : {
      62             :     RawStmt    *rawstmt;
      63             :     CachedPlanSource *plansource;
      64        1576 :     Oid        *argtypes = NULL;
      65             :     int         nargs;
      66             :     List       *query_list;
      67             : 
      68             :     /*
      69             :      * Disallow empty-string statement name (conflicts with protocol-level
      70             :      * unnamed statement).
      71             :      */
      72        1576 :     if (!stmt->name || stmt->name[0] == '\0')
      73           0 :         ereport(ERROR,
      74             :                 (errcode(ERRCODE_INVALID_PSTATEMENT_DEFINITION),
      75             :                  errmsg("invalid statement name: must not be empty")));
      76             : 
      77             :     /*
      78             :      * Need to wrap the contained statement in a RawStmt node to pass it to
      79             :      * parse analysis.
      80             :      */
      81        1576 :     rawstmt = makeNode(RawStmt);
      82        1576 :     rawstmt->stmt = stmt->query;
      83        1576 :     rawstmt->stmt_location = stmt_location;
      84        1576 :     rawstmt->stmt_len = stmt_len;
      85             : 
      86             :     /*
      87             :      * Create the CachedPlanSource before we do parse analysis, since it needs
      88             :      * to see the unmodified raw parse tree.
      89             :      */
      90        1576 :     plansource = CreateCachedPlan(rawstmt, pstate->p_sourcetext,
      91             :                                   CreateCommandTag(stmt->query));
      92             : 
      93             :     /* Transform list of TypeNames to array of type OIDs */
      94        1576 :     nargs = list_length(stmt->argtypes);
      95             : 
      96        1576 :     if (nargs)
      97             :     {
      98             :         int         i;
      99             :         ListCell   *l;
     100             : 
     101        1316 :         argtypes = palloc_array(Oid, nargs);
     102        1316 :         i = 0;
     103             : 
     104        2790 :         foreach(l, stmt->argtypes)
     105             :         {
     106        1480 :             TypeName   *tn = lfirst(l);
     107        1480 :             Oid         toid = typenameTypeId(pstate, tn);
     108             : 
     109        1474 :             argtypes[i++] = toid;
     110             :         }
     111             :     }
     112             : 
     113             :     /*
     114             :      * Analyze the statement using these parameter types (any parameters
     115             :      * passed in from above us will not be visible to it), allowing
     116             :      * information about unknown parameters to be deduced from context.
     117             :      * Rewrite the query. The result could be 0, 1, or many queries.
     118             :      */
     119        1570 :     query_list = pg_analyze_and_rewrite_varparams(rawstmt, pstate->p_sourcetext,
     120             :                                                   &argtypes, &nargs, NULL);
     121             : 
     122             :     /* Finish filling in the CachedPlanSource */
     123        1570 :     CompleteCachedPlan(plansource,
     124             :                        query_list,
     125             :                        NULL,
     126             :                        argtypes,
     127             :                        nargs,
     128             :                        NULL,
     129             :                        NULL,
     130             :                        CURSOR_OPT_PARALLEL_OK,  /* allow parallel mode */
     131             :                        true);   /* fixed result */
     132             : 
     133             :     /*
     134             :      * Save the results.
     135             :      */
     136        1570 :     StorePreparedStatement(stmt->name,
     137             :                            plansource,
     138             :                            true);
     139        1564 : }
     140             : 
     141             : /*
     142             :  * ExecuteQuery --- implement the 'EXECUTE' utility statement.
     143             :  *
     144             :  * This code also supports CREATE TABLE ... AS EXECUTE.  That case is
     145             :  * indicated by passing a non-null intoClause.  The DestReceiver is already
     146             :  * set up correctly for CREATE TABLE AS, but we still have to make a few
     147             :  * other adjustments here.
     148             :  */
     149             : void
     150        9112 : ExecuteQuery(ParseState *pstate,
     151             :              ExecuteStmt *stmt, IntoClause *intoClause,
     152             :              ParamListInfo params,
     153             :              DestReceiver *dest, QueryCompletion *qc)
     154             : {
     155             :     PreparedStatement *entry;
     156             :     CachedPlan *cplan;
     157             :     List       *plan_list;
     158        9112 :     ParamListInfo paramLI = NULL;
     159        9112 :     EState     *estate = NULL;
     160             :     Portal      portal;
     161             :     char       *query_string;
     162             :     int         eflags;
     163             :     long        count;
     164             : 
     165             :     /* Look it up in the hash table */
     166        9112 :     entry = FetchPreparedStatement(stmt->name, true);
     167             : 
     168             :     /* Shouldn't find a non-fixed-result cached plan */
     169        9112 :     if (!entry->plansource->fixed_result)
     170           0 :         elog(ERROR, "EXECUTE does not support variable-result cached plans");
     171             : 
     172             :     /* Evaluate parameters, if any */
     173        9112 :     if (entry->plansource->num_params > 0)
     174             :     {
     175             :         /*
     176             :          * Need an EState to evaluate parameters; must not delete it till end
     177             :          * of query, in case parameters are pass-by-reference.  Note that the
     178             :          * passed-in "params" could possibly be referenced in the parameter
     179             :          * expressions.
     180             :          */
     181        8200 :         estate = CreateExecutorState();
     182        8200 :         estate->es_param_list_info = params;
     183        8200 :         paramLI = EvaluateParams(pstate, entry, stmt->params, estate);
     184             :     }
     185             : 
     186             :     /* Create a new portal to run the query in */
     187        9076 :     portal = CreateNewPortal();
     188             :     /* Don't display the portal in pg_cursors, it is for internal use only */
     189        9076 :     portal->visible = false;
     190             : 
     191             :     /* Copy the plan's saved query string into the portal's memory */
     192        9076 :     query_string = MemoryContextStrdup(portal->portalContext,
     193        9076 :                                        entry->plansource->query_string);
     194             : 
     195             :     /* Replan if needed, and increment plan refcount for portal */
     196        9076 :     cplan = GetCachedPlan(entry->plansource, paramLI, NULL, NULL);
     197        9046 :     plan_list = cplan->stmt_list;
     198             : 
     199             :     /*
     200             :      * DO NOT add any logic that could possibly throw an error between
     201             :      * GetCachedPlan and PortalDefineQuery, or you'll leak the plan refcount.
     202             :      */
     203        9046 :     PortalDefineQuery(portal,
     204             :                       NULL,
     205             :                       query_string,
     206        9046 :                       entry->plansource->commandTag,
     207             :                       plan_list,
     208             :                       cplan);
     209             : 
     210             :     /*
     211             :      * For CREATE TABLE ... AS EXECUTE, we must verify that the prepared
     212             :      * statement is one that produces tuples.  Currently we insist that it be
     213             :      * a plain old SELECT.  In future we might consider supporting other
     214             :      * things such as INSERT ... RETURNING, but there are a couple of issues
     215             :      * to be settled first, notably how WITH NO DATA should be handled in such
     216             :      * a case (do we really want to suppress execution?) and how to pass down
     217             :      * the OID-determining eflags (PortalStart won't handle them in such a
     218             :      * case, and for that matter it's not clear the executor will either).
     219             :      *
     220             :      * For CREATE TABLE ... AS EXECUTE, we also have to ensure that the proper
     221             :      * eflags and fetch count are passed to PortalStart/PortalRun.
     222             :      */
     223        9046 :     if (intoClause)
     224             :     {
     225             :         PlannedStmt *pstmt;
     226             : 
     227          42 :         if (list_length(plan_list) != 1)
     228           0 :             ereport(ERROR,
     229             :                     (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     230             :                      errmsg("prepared statement is not a SELECT")));
     231          42 :         pstmt = linitial_node(PlannedStmt, plan_list);
     232          42 :         if (pstmt->commandType != CMD_SELECT)
     233           0 :             ereport(ERROR,
     234             :                     (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     235             :                      errmsg("prepared statement is not a SELECT")));
     236             : 
     237             :         /* Set appropriate eflags */
     238          42 :         eflags = GetIntoRelEFlags(intoClause);
     239             : 
     240             :         /* And tell PortalRun whether to run to completion or not */
     241          42 :         if (intoClause->skipData)
     242          12 :             count = 0;
     243             :         else
     244          30 :             count = FETCH_ALL;
     245             :     }
     246             :     else
     247             :     {
     248             :         /* Plain old EXECUTE */
     249        9004 :         eflags = 0;
     250        9004 :         count = FETCH_ALL;
     251             :     }
     252             : 
     253             :     /*
     254             :      * Run the portal as appropriate.
     255             :      */
     256        9046 :     PortalStart(portal, paramLI, eflags, GetActiveSnapshot());
     257             : 
     258        9046 :     (void) PortalRun(portal, count, false, true, dest, dest, qc);
     259             : 
     260        9014 :     PortalDrop(portal, false);
     261             : 
     262        9014 :     if (estate)
     263        8128 :         FreeExecutorState(estate);
     264             : 
     265             :     /* No need to pfree other memory, MemoryContext will be reset */
     266        9014 : }
     267             : 
     268             : /*
     269             :  * EvaluateParams: evaluate a list of parameters.
     270             :  *
     271             :  * pstate: parse state
     272             :  * pstmt: statement we are getting parameters for.
     273             :  * params: list of given parameter expressions (raw parser output!)
     274             :  * estate: executor state to use.
     275             :  *
     276             :  * Returns a filled-in ParamListInfo -- this can later be passed to
     277             :  * CreateQueryDesc(), which allows the executor to make use of the parameters
     278             :  * during query execution.
     279             :  */
     280             : static ParamListInfo
     281        8438 : EvaluateParams(ParseState *pstate, PreparedStatement *pstmt, List *params,
     282             :                EState *estate)
     283             : {
     284        8438 :     Oid        *param_types = pstmt->plansource->param_types;
     285        8438 :     int         num_params = pstmt->plansource->num_params;
     286        8438 :     int         nparams = list_length(params);
     287             :     ParamListInfo paramLI;
     288             :     List       *exprstates;
     289             :     ListCell   *l;
     290             :     int         i;
     291             : 
     292        8438 :     if (nparams != num_params)
     293          12 :         ereport(ERROR,
     294             :                 (errcode(ERRCODE_SYNTAX_ERROR),
     295             :                  errmsg("wrong number of parameters for prepared statement \"%s\"",
     296             :                         pstmt->stmt_name),
     297             :                  errdetail("Expected %d parameters but got %d.",
     298             :                            num_params, nparams)));
     299             : 
     300             :     /* Quick exit if no parameters */
     301        8426 :     if (num_params == 0)
     302           0 :         return NULL;
     303             : 
     304             :     /*
     305             :      * We have to run parse analysis for the expressions.  Since the parser is
     306             :      * not cool about scribbling on its input, copy first.
     307             :      */
     308        8426 :     params = copyObject(params);
     309             : 
     310        8426 :     i = 0;
     311       17162 :     foreach(l, params)
     312             :     {
     313        8748 :         Node       *expr = lfirst(l);
     314        8748 :         Oid         expected_type_id = param_types[i];
     315             :         Oid         given_type_id;
     316             : 
     317        8748 :         expr = transformExpr(pstate, expr, EXPR_KIND_EXECUTE_PARAMETER);
     318             : 
     319        8748 :         given_type_id = exprType(expr);
     320             : 
     321        8748 :         expr = coerce_to_target_type(pstate, expr, given_type_id,
     322             :                                      expected_type_id, -1,
     323             :                                      COERCION_ASSIGNMENT,
     324             :                                      COERCE_IMPLICIT_CAST,
     325             :                                      -1);
     326             : 
     327        8742 :         if (expr == NULL)
     328           6 :             ereport(ERROR,
     329             :                     (errcode(ERRCODE_DATATYPE_MISMATCH),
     330             :                      errmsg("parameter $%d of type %s cannot be coerced to the expected type %s",
     331             :                             i + 1,
     332             :                             format_type_be(given_type_id),
     333             :                             format_type_be(expected_type_id)),
     334             :                      errhint("You will need to rewrite or cast the expression."),
     335             :                      parser_errposition(pstate, exprLocation(lfirst(l)))));
     336             : 
     337             :         /* Take care of collations in the finished expression. */
     338        8736 :         assign_expr_collations(pstate, expr);
     339             : 
     340        8736 :         lfirst(l) = expr;
     341        8736 :         i++;
     342             :     }
     343             : 
     344             :     /* Prepare the expressions for execution */
     345        8414 :     exprstates = ExecPrepareExprList(params, estate);
     346             : 
     347        8414 :     paramLI = makeParamList(num_params);
     348             : 
     349        8414 :     i = 0;
     350       17126 :     foreach(l, exprstates)
     351             :     {
     352        8724 :         ExprState  *n = (ExprState *) lfirst(l);
     353        8724 :         ParamExternData *prm = &paramLI->params[i];
     354             : 
     355        8724 :         prm->ptype = param_types[i];
     356        8724 :         prm->pflags = PARAM_FLAG_CONST;
     357        8724 :         prm->value = ExecEvalExprSwitchContext(n,
     358        8724 :                                                GetPerTupleExprContext(estate),
     359             :                                                &prm->isnull);
     360             : 
     361        8712 :         i++;
     362             :     }
     363             : 
     364        8402 :     return paramLI;
     365             : }
     366             : 
     367             : 
     368             : /*
     369             :  * Initialize query hash table upon first use.
     370             :  */
     371             : static void
     372         880 : InitQueryHashTable(void)
     373             : {
     374             :     HASHCTL     hash_ctl;
     375             : 
     376         880 :     hash_ctl.keysize = NAMEDATALEN;
     377         880 :     hash_ctl.entrysize = sizeof(PreparedStatement);
     378             : 
     379         880 :     prepared_queries = hash_create("Prepared Queries",
     380             :                                    32,
     381             :                                    &hash_ctl,
     382             :                                    HASH_ELEM | HASH_STRINGS);
     383         880 : }
     384             : 
     385             : /*
     386             :  * Store all the data pertaining to a query in the hash table using
     387             :  * the specified key.  The passed CachedPlanSource should be "unsaved"
     388             :  * in case we get an error here; we'll save it once we've created the hash
     389             :  * table entry.
     390             :  */
     391             : void
     392        5820 : StorePreparedStatement(const char *stmt_name,
     393             :                        CachedPlanSource *plansource,
     394             :                        bool from_sql)
     395             : {
     396             :     PreparedStatement *entry;
     397        5820 :     TimestampTz cur_ts = GetCurrentStatementStartTimestamp();
     398             :     bool        found;
     399             : 
     400             :     /* Initialize the hash table, if necessary */
     401        5820 :     if (!prepared_queries)
     402         880 :         InitQueryHashTable();
     403             : 
     404             :     /* Add entry to hash table */
     405        5820 :     entry = (PreparedStatement *) hash_search(prepared_queries,
     406             :                                               stmt_name,
     407             :                                               HASH_ENTER,
     408             :                                               &found);
     409             : 
     410             :     /* Shouldn't get a duplicate entry */
     411        5820 :     if (found)
     412           6 :         ereport(ERROR,
     413             :                 (errcode(ERRCODE_DUPLICATE_PSTATEMENT),
     414             :                  errmsg("prepared statement \"%s\" already exists",
     415             :                         stmt_name)));
     416             : 
     417             :     /* Fill in the hash table entry */
     418        5814 :     entry->plansource = plansource;
     419        5814 :     entry->from_sql = from_sql;
     420        5814 :     entry->prepare_time = cur_ts;
     421             : 
     422             :     /* Now it's safe to move the CachedPlanSource to permanent memory */
     423        5814 :     SaveCachedPlan(plansource);
     424        5814 : }
     425             : 
     426             : /*
     427             :  * Lookup an existing query in the hash table. If the query does not
     428             :  * actually exist, throw ereport(ERROR) or return NULL per second parameter.
     429             :  *
     430             :  * Note: this does not force the referenced plancache entry to be valid,
     431             :  * since not all callers care.
     432             :  */
     433             : PreparedStatement *
     434       66684 : FetchPreparedStatement(const char *stmt_name, bool throwError)
     435             : {
     436             :     PreparedStatement *entry;
     437             : 
     438             :     /*
     439             :      * If the hash table hasn't been initialized, it can't be storing
     440             :      * anything, therefore it couldn't possibly store our plan.
     441             :      */
     442       66684 :     if (prepared_queries)
     443       66682 :         entry = (PreparedStatement *) hash_search(prepared_queries,
     444             :                                                   stmt_name,
     445             :                                                   HASH_FIND,
     446             :                                                   NULL);
     447             :     else
     448           2 :         entry = NULL;
     449             : 
     450       66684 :     if (!entry && throwError)
     451           2 :         ereport(ERROR,
     452             :                 (errcode(ERRCODE_UNDEFINED_PSTATEMENT),
     453             :                  errmsg("prepared statement \"%s\" does not exist",
     454             :                         stmt_name)));
     455             : 
     456       66682 :     return entry;
     457             : }
     458             : 
     459             : /*
     460             :  * Given a prepared statement, determine the result tupledesc it will
     461             :  * produce.  Returns NULL if the execution will not return tuples.
     462             :  *
     463             :  * Note: the result is created or copied into current memory context.
     464             :  */
     465             : TupleDesc
     466        8956 : FetchPreparedStatementResultDesc(PreparedStatement *stmt)
     467             : {
     468             :     /*
     469             :      * Since we don't allow prepared statements' result tupdescs to change,
     470             :      * there's no need to worry about revalidating the cached plan here.
     471             :      */
     472             :     Assert(stmt->plansource->fixed_result);
     473        8956 :     if (stmt->plansource->resultDesc)
     474        8956 :         return CreateTupleDescCopy(stmt->plansource->resultDesc);
     475             :     else
     476           0 :         return NULL;
     477             : }
     478             : 
     479             : /*
     480             :  * Given a prepared statement that returns tuples, extract the query
     481             :  * targetlist.  Returns NIL if the statement doesn't have a determinable
     482             :  * targetlist.
     483             :  *
     484             :  * Note: this is pretty ugly, but since it's only used in corner cases like
     485             :  * Describe Statement on an EXECUTE command, we don't worry too much about
     486             :  * efficiency.
     487             :  */
     488             : List *
     489        8888 : FetchPreparedStatementTargetList(PreparedStatement *stmt)
     490             : {
     491             :     List       *tlist;
     492             : 
     493             :     /* Get the plan's primary targetlist */
     494        8888 :     tlist = CachedPlanGetTargetList(stmt->plansource, NULL);
     495             : 
     496             :     /* Copy into caller's context in case plan gets invalidated */
     497        8888 :     return copyObject(tlist);
     498             : }
     499             : 
     500             : /*
     501             :  * Implements the 'DEALLOCATE' utility statement: deletes the
     502             :  * specified plan from storage.
     503             :  */
     504             : void
     505        4024 : DeallocateQuery(DeallocateStmt *stmt)
     506             : {
     507        4024 :     if (stmt->name)
     508        3978 :         DropPreparedStatement(stmt->name, true);
     509             :     else
     510          46 :         DropAllPreparedStatements();
     511        4024 : }
     512             : 
     513             : /*
     514             :  * Internal version of DEALLOCATE
     515             :  *
     516             :  * If showError is false, dropping a nonexistent statement is a no-op.
     517             :  */
     518             : void
     519        3978 : DropPreparedStatement(const char *stmt_name, bool showError)
     520             : {
     521             :     PreparedStatement *entry;
     522             : 
     523             :     /* Find the query's hash table entry; raise error if wanted */
     524        3978 :     entry = FetchPreparedStatement(stmt_name, showError);
     525             : 
     526        3978 :     if (entry)
     527             :     {
     528             :         /* Release the plancache entry */
     529        3978 :         DropCachedPlan(entry->plansource);
     530             : 
     531             :         /* Now we can remove the hash table entry */
     532        3978 :         hash_search(prepared_queries, entry->stmt_name, HASH_REMOVE, NULL);
     533             :     }
     534        3978 : }
     535             : 
     536             : /*
     537             :  * Drop all cached statements.
     538             :  */
     539             : void
     540          52 : DropAllPreparedStatements(void)
     541             : {
     542             :     HASH_SEQ_STATUS seq;
     543             :     PreparedStatement *entry;
     544             : 
     545             :     /* nothing cached */
     546          52 :     if (!prepared_queries)
     547           0 :         return;
     548             : 
     549             :     /* walk over cache */
     550          52 :     hash_seq_init(&seq, prepared_queries);
     551         118 :     while ((entry = hash_seq_search(&seq)) != NULL)
     552             :     {
     553             :         /* Release the plancache entry */
     554          66 :         DropCachedPlan(entry->plansource);
     555             : 
     556             :         /* Now we can remove the hash table entry */
     557          66 :         hash_search(prepared_queries, entry->stmt_name, HASH_REMOVE, NULL);
     558             :     }
     559             : }
     560             : 
     561             : /*
     562             :  * Implements the 'EXPLAIN EXECUTE' utility statement.
     563             :  *
     564             :  * "into" is NULL unless we are doing EXPLAIN CREATE TABLE AS EXECUTE,
     565             :  * in which case executing the query should result in creating that table.
     566             :  *
     567             :  * Note: the passed-in queryString is that of the EXPLAIN EXECUTE,
     568             :  * not the original PREPARE; we get the latter string from the plancache.
     569             :  */
     570             : void
     571         362 : ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into, ExplainState *es,
     572             :                     const char *queryString, ParamListInfo params,
     573             :                     QueryEnvironment *queryEnv)
     574             : {
     575             :     PreparedStatement *entry;
     576             :     const char *query_string;
     577             :     CachedPlan *cplan;
     578             :     List       *plan_list;
     579             :     ListCell   *p;
     580         362 :     ParamListInfo paramLI = NULL;
     581         362 :     EState     *estate = NULL;
     582             :     instr_time  planstart;
     583             :     instr_time  planduration;
     584             :     BufferUsage bufusage_start,
     585             :                 bufusage;
     586             : 
     587         362 :     if (es->buffers)
     588           0 :         bufusage_start = pgBufferUsage;
     589         362 :     INSTR_TIME_SET_CURRENT(planstart);
     590             : 
     591             :     /* Look it up in the hash table */
     592         362 :     entry = FetchPreparedStatement(execstmt->name, true);
     593             : 
     594             :     /* Shouldn't find a non-fixed-result cached plan */
     595         362 :     if (!entry->plansource->fixed_result)
     596           0 :         elog(ERROR, "EXPLAIN EXECUTE does not support variable-result cached plans");
     597             : 
     598         362 :     query_string = entry->plansource->query_string;
     599             : 
     600             :     /* Evaluate parameters, if any */
     601         362 :     if (entry->plansource->num_params)
     602             :     {
     603             :         ParseState *pstate;
     604             : 
     605         238 :         pstate = make_parsestate(NULL);
     606         238 :         pstate->p_sourcetext = queryString;
     607             : 
     608             :         /*
     609             :          * Need an EState to evaluate parameters; must not delete it till end
     610             :          * of query, in case parameters are pass-by-reference.  Note that the
     611             :          * passed-in "params" could possibly be referenced in the parameter
     612             :          * expressions.
     613             :          */
     614         238 :         estate = CreateExecutorState();
     615         238 :         estate->es_param_list_info = params;
     616             : 
     617         238 :         paramLI = EvaluateParams(pstate, entry, execstmt->params, estate);
     618             :     }
     619             : 
     620             :     /* Replan if needed, and acquire a transient refcount */
     621         362 :     cplan = GetCachedPlan(entry->plansource, paramLI,
     622             :                           CurrentResourceOwner, queryEnv);
     623             : 
     624         362 :     INSTR_TIME_SET_CURRENT(planduration);
     625         362 :     INSTR_TIME_SUBTRACT(planduration, planstart);
     626             : 
     627             :     /* calc differences of buffer counters. */
     628         362 :     if (es->buffers)
     629             :     {
     630           0 :         memset(&bufusage, 0, sizeof(BufferUsage));
     631           0 :         BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start);
     632             :     }
     633             : 
     634         362 :     plan_list = cplan->stmt_list;
     635             : 
     636             :     /* Explain each query */
     637         724 :     foreach(p, plan_list)
     638             :     {
     639         362 :         PlannedStmt *pstmt = lfirst_node(PlannedStmt, p);
     640             : 
     641         362 :         if (pstmt->commandType != CMD_UTILITY)
     642         362 :             ExplainOnePlan(pstmt, into, es, query_string, paramLI, queryEnv,
     643         362 :                            &planduration, (es->buffers ? &bufusage : NULL));
     644             :         else
     645           0 :             ExplainOneUtility(pstmt->utilityStmt, into, es, query_string,
     646             :                               paramLI, queryEnv);
     647             : 
     648             :         /* No need for CommandCounterIncrement, as ExplainOnePlan did it */
     649             : 
     650             :         /* Separate plans with an appropriate separator */
     651         362 :         if (lnext(plan_list, p) != NULL)
     652           0 :             ExplainSeparatePlans(es);
     653             :     }
     654             : 
     655         362 :     if (estate)
     656         238 :         FreeExecutorState(estate);
     657             : 
     658         362 :     ReleaseCachedPlan(cplan, CurrentResourceOwner);
     659         362 : }
     660             : 
     661             : /*
     662             :  * This set returning function reads all the prepared statements and
     663             :  * returns a set of (name, statement, prepare_time, param_types, from_sql,
     664             :  * generic_plans, custom_plans).
     665             :  */
     666             : Datum
     667          96 : pg_prepared_statement(PG_FUNCTION_ARGS)
     668             : {
     669          96 :     ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
     670             : 
     671             :     /*
     672             :      * We put all the tuples into a tuplestore in one scan of the hashtable.
     673             :      * This avoids any issue of the hashtable possibly changing between calls.
     674             :      */
     675          96 :     InitMaterializedSRF(fcinfo, 0);
     676             : 
     677             :     /* hash table might be uninitialized */
     678          96 :     if (prepared_queries)
     679             :     {
     680             :         HASH_SEQ_STATUS hash_seq;
     681             :         PreparedStatement *prep_stmt;
     682             : 
     683          84 :         hash_seq_init(&hash_seq, prepared_queries);
     684         366 :         while ((prep_stmt = hash_seq_search(&hash_seq)) != NULL)
     685             :         {
     686             :             TupleDesc   result_desc;
     687             :             Datum       values[8];
     688         282 :             bool        nulls[8] = {0};
     689             : 
     690         282 :             result_desc = prep_stmt->plansource->resultDesc;
     691             : 
     692         282 :             values[0] = CStringGetTextDatum(prep_stmt->stmt_name);
     693         282 :             values[1] = CStringGetTextDatum(prep_stmt->plansource->query_string);
     694         282 :             values[2] = TimestampTzGetDatum(prep_stmt->prepare_time);
     695         564 :             values[3] = build_regtype_array(prep_stmt->plansource->param_types,
     696         282 :                                             prep_stmt->plansource->num_params);
     697         282 :             if (result_desc)
     698             :             {
     699             :                 Oid        *result_types;
     700             : 
     701         276 :                 result_types = palloc_array(Oid, result_desc->natts);
     702         948 :                 for (int i = 0; i < result_desc->natts; i++)
     703         672 :                     result_types[i] = result_desc->attrs[i].atttypid;
     704         276 :                 values[4] = build_regtype_array(result_types, result_desc->natts);
     705             :             }
     706             :             else
     707             :             {
     708             :                 /* no result descriptor (for example, DML statement) */
     709           6 :                 nulls[4] = true;
     710             :             }
     711         282 :             values[5] = BoolGetDatum(prep_stmt->from_sql);
     712         282 :             values[6] = Int64GetDatumFast(prep_stmt->plansource->num_generic_plans);
     713         282 :             values[7] = Int64GetDatumFast(prep_stmt->plansource->num_custom_plans);
     714             : 
     715         282 :             tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
     716             :                                  values, nulls);
     717             :         }
     718             :     }
     719             : 
     720          96 :     return (Datum) 0;
     721             : }
     722             : 
     723             : /*
     724             :  * This utility function takes a C array of Oids, and returns a Datum
     725             :  * pointing to a one-dimensional Postgres array of regtypes. An empty
     726             :  * array is returned as a zero-element array, not NULL.
     727             :  */
     728             : static Datum
     729         558 : build_regtype_array(Oid *param_types, int num_params)
     730             : {
     731             :     Datum      *tmp_ary;
     732             :     ArrayType  *result;
     733             :     int         i;
     734             : 
     735         558 :     tmp_ary = palloc_array(Datum, num_params);
     736             : 
     737        1380 :     for (i = 0; i < num_params; i++)
     738         822 :         tmp_ary[i] = ObjectIdGetDatum(param_types[i]);
     739             : 
     740         558 :     result = construct_array_builtin(tmp_ary, num_params, REGTYPEOID);
     741         558 :     return PointerGetDatum(result);
     742             : }

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