prepare.h File Reference

#include "commands/explain.h"
#include "datatype/timestamp.h"
#include "utils/plancache.h"

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Data Structures
struct	PreparedStatement

Functions
void	PrepareQuery (ParseState *pstate, PrepareStmt *stmt, int stmt_location, int stmt_len)
void	ExecuteQuery (ParseState *pstate, ExecuteStmt *stmt, IntoClause *intoClause, ParamListInfo params, DestReceiver *dest, QueryCompletion *qc)
void	DeallocateQuery (DeallocateStmt *stmt)
void	ExplainExecuteQuery (ExecuteStmt *execstmt, IntoClause *into, ExplainState *es, const char *queryString, ParamListInfo params, QueryEnvironment *queryEnv)
void	StorePreparedStatement (const char *stmt_name, CachedPlanSource *plansource, bool from_sql)
PreparedStatement *	FetchPreparedStatement (const char *stmt_name, bool throwError)
void	DropPreparedStatement (const char *stmt_name, bool showError)
TupleDesc	FetchPreparedStatementResultDesc (PreparedStatement *stmt)
List *	FetchPreparedStatementTargetList (PreparedStatement *stmt)
void	DropAllPreparedStatements (void)

Function Documentation

DeallocateQuery()

void DeallocateQuery

(

DeallocateStmt *

stmt

)

Definition at line 539 of file prepare.c.

References DropAllPreparedStatements(), DropPreparedStatement(), and DeallocateStmt::name.

Referenced by standard_ProcessUtility().

{
    if (stmt->name)
        DropPreparedStatement(stmt->name, true);
    else
        DropAllPreparedStatements();
}

DropAllPreparedStatements()

void DropAllPreparedStatements

(

void

)

Definition at line 574 of file prepare.c.

References DropCachedPlan(), HASH_REMOVE, hash_search(), hash_seq_init(), hash_seq_search(), PreparedStatement::plansource, and PreparedStatement::stmt_name.

Referenced by DeallocateQuery(), and DiscardAll().

{
    HASH_SEQ_STATUS seq;
    PreparedStatement *entry;

    /* nothing cached */
    if (!prepared_queries)
        return;

    /* walk over cache */
    hash_seq_init(&seq, prepared_queries);
    while ((entry = hash_seq_search(&seq)) != NULL)
    {
        /* Release the plancache entry */
        DropCachedPlan(entry->plansource);

        /* Now we can remove the hash table entry */
        hash_search(prepared_queries, entry->stmt_name, HASH_REMOVE, NULL);
    }
}

DropPreparedStatement()

void DropPreparedStatement	(	const char *	stmt_name,
		bool	showError
	)

Definition at line 553 of file prepare.c.

References DropCachedPlan(), FetchPreparedStatement(), HASH_REMOVE, hash_search(), PreparedStatement::plansource, and PreparedStatement::stmt_name.

Referenced by DeallocateQuery(), and PostgresMain().

{
    PreparedStatement *entry;

    /* Find the query's hash table entry; raise error if wanted */
    entry = FetchPreparedStatement(stmt_name, showError);

    if (entry)
    {
        /* Release the plancache entry */
        DropCachedPlan(entry->plansource);

        /* Now we can remove the hash table entry */
        hash_search(prepared_queries, entry->stmt_name, HASH_REMOVE, NULL);
    }
}

ExecuteQuery()

void ExecuteQuery	(	ParseState *	pstate,
		ExecuteStmt *	stmt,
		IntoClause *	intoClause,
		ParamListInfo	params,
		DestReceiver *	dest,
		QueryCompletion *	qc
	)

Definition at line 184 of file prepare.c.

References CMD_SELECT, CachedPlanSource::commandTag, PlannedStmt::commandType, CreateExecutorState(), CreateNewPortal(), elog, ereport, errcode(), errmsg(), ERROR, EState::es_param_list_info, EvaluateParams(), FETCH_ALL, FetchPreparedStatement(), CachedPlanSource::fixed_result, FreeExecutorState(), GetActiveSnapshot(), GetCachedPlan(), GetIntoRelEFlags(), linitial_node, list_length(), MemoryContextStrdup(), ExecuteStmt::name, CachedPlanSource::num_params, ExecuteStmt::params, PreparedStatement::plansource, PortalData::portalContext, PortalDefineQuery(), PortalDrop(), PortalRun(), PortalStart(), CachedPlanSource::query_string, IntoClause::skipData, CachedPlan::stmt_list, and PortalData::visible.

Referenced by ExecCreateTableAs(), and standard_ProcessUtility().

{
    PreparedStatement *entry;
    CachedPlan *cplan;
    List       *plan_list;
    ParamListInfo paramLI = NULL;
    EState     *estate = NULL;
    Portal      portal;
    char       *query_string;
    int         eflags;
    long        count;

    /* Look it up in the hash table */
    entry = FetchPreparedStatement(stmt->name, true);

    /* Shouldn't find a non-fixed-result cached plan */
    if (!entry->plansource->fixed_result)
        elog(ERROR, "EXECUTE does not support variable-result cached plans");

    /* Evaluate parameters, if any */
    if (entry->plansource->num_params > 0)
    {
        /*
         * Need an EState to evaluate parameters; must not delete it till end
         * of query, in case parameters are pass-by-reference.  Note that the
         * passed-in "params" could possibly be referenced in the parameter
         * expressions.
         */
        estate = CreateExecutorState();
        estate->es_param_list_info = params;
        paramLI = EvaluateParams(pstate, entry, stmt->params, estate);
    }

    /* Create a new portal to run the query in */
    portal = CreateNewPortal();
    /* Don't display the portal in pg_cursors, it is for internal use only */
    portal->visible = false;

    /* Copy the plan's saved query string into the portal's memory */
    query_string = MemoryContextStrdup(portal->portalContext,
                                       entry->plansource->query_string);

    /* Replan if needed, and increment plan refcount for portal */
    cplan = GetCachedPlan(entry->plansource, paramLI, NULL, NULL);
    plan_list = cplan->stmt_list;

    /*
     * DO NOT add any logic that could possibly throw an error between
     * GetCachedPlan and PortalDefineQuery, or you'll leak the plan refcount.
     */
    PortalDefineQuery(portal,
                      NULL,
                      query_string,
                      entry->plansource->commandTag,
                      plan_list,
                      cplan);

    /*
     * For CREATE TABLE ... AS EXECUTE, we must verify that the prepared
     * statement is one that produces tuples.  Currently we insist that it be
     * a plain old SELECT.  In future we might consider supporting other
     * things such as INSERT ... RETURNING, but there are a couple of issues
     * to be settled first, notably how WITH NO DATA should be handled in such
     * a case (do we really want to suppress execution?) and how to pass down
     * the OID-determining eflags (PortalStart won't handle them in such a
     * case, and for that matter it's not clear the executor will either).
     *
     * For CREATE TABLE ... AS EXECUTE, we also have to ensure that the proper
     * eflags and fetch count are passed to PortalStart/PortalRun.
     */
    if (intoClause)
    {
        PlannedStmt *pstmt;

        if (list_length(plan_list) != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("prepared statement is not a SELECT")));
        pstmt = linitial_node(PlannedStmt, plan_list);
        if (pstmt->commandType != CMD_SELECT)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("prepared statement is not a SELECT")));

        /* Set appropriate eflags */
        eflags = GetIntoRelEFlags(intoClause);

        /* And tell PortalRun whether to run to completion or not */
        if (intoClause->skipData)
            count = 0;
        else
            count = FETCH_ALL;
    }
    else
    {
        /* Plain old EXECUTE */
        eflags = 0;
        count = FETCH_ALL;
    }

    /*
     * Run the portal as appropriate.
     */
    PortalStart(portal, paramLI, eflags, GetActiveSnapshot());

    (void) PortalRun(portal, count, false, true, dest, dest, qc);

    PortalDrop(portal, false);

    if (estate)
        FreeExecutorState(estate);

    /* No need to pfree other memory, MemoryContext will be reset */
}

ExplainExecuteQuery()

void ExplainExecuteQuery	(	ExecuteStmt *	execstmt,
		IntoClause *	into,
		ExplainState *	es,
		const char *	queryString,
		ParamListInfo	params,
		QueryEnvironment *	queryEnv
	)

Definition at line 605 of file prepare.c.

References ExplainState::buffers, BufferUsageAccumDiff(), CMD_UTILITY, PlannedStmt::commandType, CreateExecutorState(), CurrentResourceOwner, elog, ERROR, EState::es_param_list_info, EvaluateParams(), ExplainOnePlan(), ExplainOneUtility(), ExplainSeparatePlans(), FetchPreparedStatement(), CachedPlanSource::fixed_result, FreeExecutorState(), GetCachedPlan(), INSTR_TIME_SET_CURRENT, INSTR_TIME_SUBTRACT, lfirst_node, lnext(), make_parsestate(), ExecuteStmt::name, CachedPlanSource::num_params, ParseState::p_sourcetext, ExecuteStmt::params, pgBufferUsage, PreparedStatement::plansource, CachedPlanSource::query_string, ReleaseCachedPlan(), CachedPlan::stmt_list, and PlannedStmt::utilityStmt.

Referenced by ExplainOneUtility().

{
    PreparedStatement *entry;
    const char *query_string;
    CachedPlan *cplan;
    List       *plan_list;
    ListCell   *p;
    ParamListInfo paramLI = NULL;
    EState     *estate = NULL;
    instr_time  planstart;
    instr_time  planduration;
    BufferUsage bufusage_start,
                bufusage;

    if (es->buffers)
        bufusage_start = pgBufferUsage;
    INSTR_TIME_SET_CURRENT(planstart);

    /* Look it up in the hash table */
    entry = FetchPreparedStatement(execstmt->name, true);

    /* Shouldn't find a non-fixed-result cached plan */
    if (!entry->plansource->fixed_result)
        elog(ERROR, "EXPLAIN EXECUTE does not support variable-result cached plans");

    query_string = entry->plansource->query_string;

    /* Evaluate parameters, if any */
    if (entry->plansource->num_params)
    {
        ParseState *pstate;

        pstate = make_parsestate(NULL);
        pstate->p_sourcetext = queryString;

        /*
         * Need an EState to evaluate parameters; must not delete it till end
         * of query, in case parameters are pass-by-reference.  Note that the
         * passed-in "params" could possibly be referenced in the parameter
         * expressions.
         */
        estate = CreateExecutorState();
        estate->es_param_list_info = params;

        paramLI = EvaluateParams(pstate, entry, execstmt->params, estate);
    }

    /* Replan if needed, and acquire a transient refcount */
    cplan = GetCachedPlan(entry->plansource, paramLI,
                          CurrentResourceOwner, queryEnv);

    INSTR_TIME_SET_CURRENT(planduration);
    INSTR_TIME_SUBTRACT(planduration, planstart);

    /* calc differences of buffer counters. */
    if (es->buffers)
    {
        memset(&bufusage, 0, sizeof(BufferUsage));
        BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start);
    }

    plan_list = cplan->stmt_list;

    /* Explain each query */
    foreach(p, plan_list)
    {
        PlannedStmt *pstmt = lfirst_node(PlannedStmt, p);

        if (pstmt->commandType != CMD_UTILITY)
            ExplainOnePlan(pstmt, into, es, query_string, paramLI, queryEnv,
                           &planduration, (es->buffers ? &bufusage : NULL));
        else
            ExplainOneUtility(pstmt->utilityStmt, into, es, query_string,
                              paramLI, queryEnv);

        /* No need for CommandCounterIncrement, as ExplainOnePlan did it */

        /* Separate plans with an appropriate separator */
        if (lnext(plan_list, p) != NULL)
            ExplainSeparatePlans(es);
    }

    if (estate)
        FreeExecutorState(estate);

    ReleaseCachedPlan(cplan, CurrentResourceOwner);
}

FetchPreparedStatement()

PreparedStatement* FetchPreparedStatement	(	const char *	stmt_name,
		bool	throwError
	)

Definition at line 468 of file prepare.c.

References ereport, errcode(), errmsg(), ERROR, HASH_FIND, and hash_search().

Referenced by DropPreparedStatement(), errdetail_execute(), exec_bind_message(), exec_describe_statement_message(), ExecuteQuery(), ExplainExecuteQuery(), FetchStatementTargetList(), GetCommandLogLevel(), UtilityReturnsTuples(), and UtilityTupleDescriptor().

{
    PreparedStatement *entry;

    /*
     * If the hash table hasn't been initialized, it can't be storing
     * anything, therefore it couldn't possibly store our plan.
     */
    if (prepared_queries)
        entry = (PreparedStatement *) hash_search(prepared_queries,
                                                  stmt_name,
                                                  HASH_FIND,
                                                  NULL);
    else
        entry = NULL;

    if (!entry && throwError)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_PSTATEMENT),
                 errmsg("prepared statement \"%s\" does not exist",
                        stmt_name)));

    return entry;
}

FetchPreparedStatementResultDesc()

TupleDesc FetchPreparedStatementResultDesc

(

PreparedStatement *

stmt

)

Definition at line 500 of file prepare.c.

References Assert, CreateTupleDescCopy(), CachedPlanSource::fixed_result, PreparedStatement::plansource, and CachedPlanSource::resultDesc.

Referenced by UtilityTupleDescriptor().

{
    /*
     * Since we don't allow prepared statements' result tupdescs to change,
     * there's no need to worry about revalidating the cached plan here.
     */
    Assert(stmt->plansource->fixed_result);
    if (stmt->plansource->resultDesc)
        return CreateTupleDescCopy(stmt->plansource->resultDesc);
    else
        return NULL;
}

FetchPreparedStatementTargetList()

List* FetchPreparedStatementTargetList

(

PreparedStatement *

stmt

)

Definition at line 523 of file prepare.c.

References CachedPlanGetTargetList(), copyObject, and PreparedStatement::plansource.

Referenced by FetchStatementTargetList().

{
    List       *tlist;

    /* Get the plan's primary targetlist */
    tlist = CachedPlanGetTargetList(stmt->plansource, NULL);

    /* Copy into caller's context in case plan gets invalidated */
    return copyObject(tlist);
}

PrepareQuery()

void PrepareQuery	(	ParseState *	pstate,
		PrepareStmt *	stmt,
		int	stmt_location,
		int	stmt_len
	)

Definition at line 58 of file prepare.c.

References PrepareStmt::argtypes, CMD_DELETE, CMD_INSERT, CMD_SELECT, CMD_UPDATE, Query::commandType, CompleteCachedPlan(), CreateCachedPlan(), CreateCommandTag(), CURSOR_OPT_PARALLEL_OK, ereport, errcode(), errmsg(), ERROR, i, InvalidOid, lfirst, list_length(), makeNode, PrepareStmt::name, ParseState::p_sourcetext, palloc(), parse_analyze_varparams(), PrepareStmt::query, QueryRewrite(), RawStmt::stmt, RawStmt::stmt_len, RawStmt::stmt_location, StorePreparedStatement(), and typenameTypeId().

Referenced by standard_ProcessUtility().

{
    RawStmt    *rawstmt;
    CachedPlanSource *plansource;
    Oid        *argtypes = NULL;
    int         nargs;
    Query      *query;
    List       *query_list;
    int         i;

    /*
     * Disallow empty-string statement name (conflicts with protocol-level
     * unnamed statement).
     */
    if (!stmt->name || stmt->name[0] == '\0')
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PSTATEMENT_DEFINITION),
                 errmsg("invalid statement name: must not be empty")));

    /*
     * Need to wrap the contained statement in a RawStmt node to pass it to
     * parse analysis.
     */
    rawstmt = makeNode(RawStmt);
    rawstmt->stmt = stmt->query;
    rawstmt->stmt_location = stmt_location;
    rawstmt->stmt_len = stmt_len;

    /*
     * Create the CachedPlanSource before we do parse analysis, since it needs
     * to see the unmodified raw parse tree.
     */
    plansource = CreateCachedPlan(rawstmt, pstate->p_sourcetext,
                                  CreateCommandTag(stmt->query));

    /* Transform list of TypeNames to array of type OIDs */
    nargs = list_length(stmt->argtypes);

    if (nargs)
    {
        ListCell   *l;

        argtypes = (Oid *) palloc(nargs * sizeof(Oid));
        i = 0;

        foreach(l, stmt->argtypes)
        {
            TypeName   *tn = lfirst(l);
            Oid         toid = typenameTypeId(pstate, tn);

            argtypes[i++] = toid;
        }
    }

    /*
     * Analyze the statement using these parameter types (any parameters
     * passed in from above us will not be visible to it), allowing
     * information about unknown parameters to be deduced from context.
     */
    query = parse_analyze_varparams(rawstmt, pstate->p_sourcetext,
                                    &argtypes, &nargs);

    /*
     * Check that all parameter types were determined.
     */
    for (i = 0; i < nargs; i++)
    {
        Oid         argtype = argtypes[i];

        if (argtype == InvalidOid || argtype == UNKNOWNOID)
            ereport(ERROR,
                    (errcode(ERRCODE_INDETERMINATE_DATATYPE),
                     errmsg("could not determine data type of parameter $%d",
                            i + 1)));
    }

    /*
     * grammar only allows PreparableStmt, so this check should be redundant
     */
    switch (query->commandType)
    {
        case CMD_SELECT:
        case CMD_INSERT:
        case CMD_UPDATE:
        case CMD_DELETE:
            /* OK */
            break;
        default:
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PSTATEMENT_DEFINITION),
                     errmsg("utility statements cannot be prepared")));
            break;
    }

    /* Rewrite the query. The result could be 0, 1, or many queries. */
    query_list = QueryRewrite(query);

    /* Finish filling in the CachedPlanSource */
    CompleteCachedPlan(plansource,
                       query_list,
                       NULL,
                       argtypes,
                       nargs,
                       NULL,
                       NULL,
                       CURSOR_OPT_PARALLEL_OK,  /* allow parallel mode */
                       true);   /* fixed result */

    /*
     * Save the results.
     */
    StorePreparedStatement(stmt->name,
                           plansource,
                           true);
}

StorePreparedStatement()

void StorePreparedStatement	(	const char *	stmt_name,
		CachedPlanSource *	plansource,
		bool	from_sql
	)

Definition at line 426 of file prepare.c.

References ereport, errcode(), errmsg(), ERROR, PreparedStatement::from_sql, GetCurrentStatementStartTimestamp(), HASH_ENTER, hash_search(), InitQueryHashTable(), PreparedStatement::plansource, PreparedStatement::prepare_time, and SaveCachedPlan().

Referenced by exec_parse_message(), and PrepareQuery().

{
    PreparedStatement *entry;
    TimestampTz cur_ts = GetCurrentStatementStartTimestamp();
    bool        found;

    /* Initialize the hash table, if necessary */
    if (!prepared_queries)
        InitQueryHashTable();

    /* Add entry to hash table */
    entry = (PreparedStatement *) hash_search(prepared_queries,
                                              stmt_name,
                                              HASH_ENTER,
                                              &found);

    /* Shouldn't get a duplicate entry */
    if (found)
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_PSTATEMENT),
                 errmsg("prepared statement \"%s\" already exists",
                        stmt_name)));

    /* Fill in the hash table entry */
    entry->plansource = plansource;
    entry->from_sql = from_sql;
    entry->prepare_time = cur_ts;

    /* Now it's safe to move the CachedPlanSource to permanent memory */
    SaveCachedPlan(plansource);
}