/*
* PerformCursorOpen
* Execute SQL DECLARE CURSOR command.
*
* The query has already been through parse analysis, rewriting, and planning.
* When it gets here, it looks like a SELECT PlannedStmt, except that the
* utilityStmt field is set.
*/
void
PerformCursorOpen(PlannedStmt *stmt, ParamListInfo params,
const char *queryString, bool isTopLevel)
{
DeclareCursorStmt *cstmt = (DeclareCursorStmt *) stmt->utilityStmt;
Portal portal;
MemoryContext oldContext;
if (cstmt == NULL || !IsA(cstmt, DeclareCursorStmt))
elog(ERROR, "PerformCursorOpen called for non-cursor query");
/*
* Disallow empty-string cursor name (conflicts with protocol-level
* unnamed portal).
*/
if (!cstmt->portalname || cstmt->portalname[0] == '\0')
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_NAME),
errmsg("invalid cursor name: must not be empty")));
/*
* If this is a non-holdable cursor, we require that this statement has
* been executed inside a transaction block (or else, it would have no
* user-visible effect).
*/
if (!(cstmt->options & CURSOR_OPT_HOLD))
RequireTransactionChain(isTopLevel, "DECLARE CURSOR");
/*
* Create a portal and copy the plan and queryString into its memory.
*/
portal = CreatePortal(cstmt->portalname, false, false);
oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
stmt = copyObject(stmt);
stmt->utilityStmt = NULL; /* make it look like plain SELECT */
queryString = pstrdup(queryString);
PortalDefineQuery(portal,
NULL,
queryString,
"SELECT", /* cursor's query is always a SELECT */
list_make1(stmt),
NULL);
/*----------
* Also copy the outer portal's parameter list into the inner portal's
* memory context. We want to pass down the parameter values in case we
* had a command like
* DECLARE c CURSOR FOR SELECT ... WHERE foo = $1
* This will have been parsed using the outer parameter set and the
* parameter value needs to be preserved for use when the cursor is
* executed.
*----------
*/
params = copyParamList(params);
MemoryContextSwitchTo(oldContext);
/*
* Set up options for portal.
*
* If the user didn't specify a SCROLL type, allow or disallow scrolling
* based on whether it would require any additional runtime overhead to do
* so. Also, we disallow scrolling for FOR UPDATE cursors.
*/
portal->cursorOptions = cstmt->options;
if (!(portal->cursorOptions & (CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL)))
{
if (stmt->rowMarks == NIL &&
ExecSupportsBackwardScan(stmt->planTree))
portal->cursorOptions |= CURSOR_OPT_SCROLL;
else
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
}
/*
* Start execution, inserting parameters if any.
*/
PortalStart(portal, params, GetActiveSnapshot());
Assert(portal->strategy == PORTAL_ONE_SELECT);
/*
* We're done; the query won't actually be run until PerformPortalFetch is
* called.
*/
}
/*
* SPI_cursor_open()
*
* Open a prepared SPI plan as a portal
*/
Portal
SPI_cursor_open(const char *name, void *plan,
Datum *Values, const char *Nulls,
bool read_only)
{
_SPI_plan *spiplan = (_SPI_plan *) plan;
List *qtlist = spiplan->qtlist;
List *ptlist = spiplan->ptlist;
Query *queryTree;
Plan *planTree;
ParamListInfo paramLI;
Snapshot snapshot;
MemoryContext oldcontext;
Portal portal;
int k;
/* Ensure that the plan contains only one query */
if (list_length(ptlist) != 1 || list_length(qtlist) != 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
errmsg("cannot open multi-query plan as cursor")));
queryTree = (Query *) linitial((List *) linitial(qtlist));
planTree = (Plan *) linitial(ptlist);
/* Must be a query that returns tuples */
switch (queryTree->commandType)
{
case CMD_SELECT:
if (queryTree->into != NULL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
errmsg("cannot open SELECT INTO query as cursor")));
break;
case CMD_UTILITY:
if (!UtilityReturnsTuples(queryTree->utilityStmt))
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
errmsg("cannot open non-SELECT query as cursor")));
break;
default:
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
errmsg("cannot open non-SELECT query as cursor")));
break;
}
/* Reset SPI result */
SPI_processed = 0;
SPI_tuptable = NULL;
_SPI_current->processed = 0;
_SPI_current->tuptable = NULL;
/* Create the portal */
if (name == NULL || name[0] == '\0')
{
/* Use a random nonconflicting name */
portal = CreateNewPortal();
}
else
{
/* In this path, error if portal of same name already exists */
portal = CreatePortal(name, false, false);
}
/* Switch to portals memory and copy the parsetree and plan to there */
oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
queryTree = copyObject(queryTree);
planTree = copyObject(planTree);
/* If the plan has parameters, set them up */
if (spiplan->nargs > 0)
{
paramLI = (ParamListInfo) palloc0((spiplan->nargs + 1) *
sizeof(ParamListInfoData));
for (k = 0; k < spiplan->nargs; k++)
{
paramLI[k].kind = PARAM_NUM;
paramLI[k].id = k + 1;
paramLI[k].ptype = spiplan->argtypes[k];
paramLI[k].isnull = (Nulls && Nulls[k] == 'n');
if (paramLI[k].isnull)
{
/* nulls just copy */
paramLI[k].value = Values[k];
}
else
{
/* pass-by-ref values must be copied into portal context */
int16 paramTypLen;
bool paramTypByVal;
get_typlenbyval(spiplan->argtypes[k],
¶mTypLen, ¶mTypByVal);
paramLI[k].value = datumCopy(Values[k],
paramTypByVal, paramTypLen);
}
}
paramLI[k].kind = PARAM_INVALID;
}
else
paramLI = NULL;
/*
* Set up the portal.
*/
PortalDefineQuery(portal,
NULL, /* unfortunately don't have sourceText */
"SELECT", /* nor the raw parse tree... */
list_make1(queryTree),
list_make1(planTree),
PortalGetHeapMemory(portal));
MemoryContextSwitchTo(oldcontext);
/*
* Set up options for portal.
*/
portal->cursorOptions &= ~(CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL);
if (planTree == NULL || ExecSupportsBackwardScan(planTree))
portal->cursorOptions |= CURSOR_OPT_SCROLL;
else
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
/*
* Set up the snapshot to use. (PortalStart will do CopySnapshot,
* so we skip that here.)
*/
if (read_only)
snapshot = ActiveSnapshot;
else
{
CommandCounterIncrement();
snapshot = GetTransactionSnapshot();
}
/*
* Start portal execution.
*/
PortalStart(portal, paramLI, snapshot);
Assert(portal->strategy == PORTAL_ONE_SELECT ||
portal->strategy == PORTAL_UTIL_SELECT);
/* Return the created portal */
return portal;
}
/*
* PerformCursorOpen
* Execute SQL DECLARE CURSOR command.
*/
void
PerformCursorOpen(DeclareCursorStmt *cstmt, ParamListInfo params,
const char *queryString, bool isTopLevel)
{
Query *query = (Query *) cstmt->query;
List *rewritten;
PlannedStmt *plan;
Portal portal;
MemoryContext oldContext;
Assert(IsA(query, Query)); /* else parse analysis wasn't done */
/*
* Disallow empty-string cursor name (conflicts with protocol-level
* unnamed portal).
*/
if (!cstmt->portalname || cstmt->portalname[0] == '\0')
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_NAME),
errmsg("invalid cursor name: must not be empty")));
/*
* If this is a non-holdable cursor, we require that this statement has
* been executed inside a transaction block (or else, it would have no
* user-visible effect).
*/
if (!(cstmt->options & CURSOR_OPT_HOLD))
RequireTransactionChain(isTopLevel, "DECLARE CURSOR");
/*
* Parse analysis was done already, but we still have to run the rule
* rewriter. We do not do AcquireRewriteLocks: we assume the query either
* came straight from the parser, or suitable locks were acquired by
* plancache.c.
*
* Because the rewriter and planner tend to scribble on the input, we make
* a preliminary copy of the source querytree. This prevents problems in
* the case that the DECLARE CURSOR is in a portal or plpgsql function and
* is executed repeatedly. (See also the same hack in EXPLAIN and
* PREPARE.) XXX FIXME someday.
*/
rewritten = QueryRewrite((Query *) copyObject(query));
/* SELECT should never rewrite to more or less than one query */
if (list_length(rewritten) != 1)
elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
query = (Query *) linitial(rewritten);
if (query->commandType != CMD_SELECT)
elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
/* Plan the query, applying the specified options */
plan = pg_plan_query(query, cstmt->options, params);
/*
* Create a portal and copy the plan and queryString into its memory.
*/
portal = CreatePortal(cstmt->portalname, false, false);
oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
plan = copyObject(plan);
queryString = pstrdup(queryString);
PortalDefineQuery(portal,
NULL,
queryString,
"SELECT", /* cursor's query is always a SELECT */
list_make1(plan),
NULL);
/*----------
* Also copy the outer portal's parameter list into the inner portal's
* memory context. We want to pass down the parameter values in case we
* had a command like
* DECLARE c CURSOR FOR SELECT ... WHERE foo = $1
* This will have been parsed using the outer parameter set and the
* parameter value needs to be preserved for use when the cursor is
* executed.
*----------
*/
params = copyParamList(params);
MemoryContextSwitchTo(oldContext);
/*
* Set up options for portal.
*
* If the user didn't specify a SCROLL type, allow or disallow scrolling
* based on whether it would require any additional runtime overhead to do
* so. Also, we disallow scrolling for FOR UPDATE cursors.
*/
portal->cursorOptions = cstmt->options;
if (!(portal->cursorOptions & (CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL)))
{
if (plan->rowMarks == NIL &&
ExecSupportsBackwardScan(plan->planTree))
portal->cursorOptions |= CURSOR_OPT_SCROLL;
else
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
}
/*
* Start execution, inserting parameters if any.
*/
PortalStart(portal, params, 0, GetActiveSnapshot());
Assert(portal->strategy == PORTAL_ONE_SELECT);
/*
* We're done; the query won't actually be run until PerformPortalFetch is
* called.
*/
}
/*
* CreateCitusToplevelNode creates the top-level planTree node for a
* distributed statement. That top-level node is a) recognizable by the
* executor hooks, allowing them to redirect execution, b) contains the
* parameters required for distributed execution.
*
* The exact representation of the top-level node is an implementation detail
* which should not be referred to outside this file, as it's likely to become
* version dependant. Use GetMultiPlan() and HasCitusToplevelNode() to access.
*
* Internally the data is stored as arguments to a 'citus_extradata_container'
* function, which has to be removed from the really executed plan tree before
* query execution.
*/
PlannedStmt *
MultiQueryContainerNode(PlannedStmt *result, MultiPlan *multiPlan)
{
FunctionScan *fauxFunctionScan = NULL;
RangeTblFunction *fauxFunction = NULL;
FuncExpr *fauxFuncExpr = NULL;
Const *multiPlanData = NULL;
char *serializedPlan = NULL;
/* pass multiPlan serialized as a constant function argument */
serializedPlan = CitusNodeToString(multiPlan);
multiPlanData = makeNode(Const);
multiPlanData->consttype = CSTRINGOID;
multiPlanData->constlen = strlen(serializedPlan);
multiPlanData->constvalue = CStringGetDatum(serializedPlan);
multiPlanData->constbyval = false;
multiPlanData->location = -1;
fauxFuncExpr = makeNode(FuncExpr);
fauxFuncExpr->funcid = CitusExtraDataContainerFuncId();
fauxFuncExpr->funcretset = true;
fauxFuncExpr->location = -1;
fauxFuncExpr->args = list_make1(multiPlanData);
fauxFunction = makeNode(RangeTblFunction);
fauxFunction->funcexpr = (Node *) fauxFuncExpr;
fauxFunctionScan = makeNode(FunctionScan);
fauxFunctionScan->functions = lappend(fauxFunctionScan->functions, fauxFunction);
/* copy original targetlist, accessed for RETURNING queries */
fauxFunctionScan->scan.plan.targetlist = copyObject(result->planTree->targetlist);
/*
* Add set returning function to target list if the original (postgres
* created) plan doesn't support backward scans; doing so prevents
* backward scans being supported by the new plantree as well. This is
* ugly as hell, but until we can rely on custom scans (which can signal
* this via CUSTOMPATH_SUPPORT_BACKWARD_SCAN), there's not really a pretty
* method to achieve this.
*
* FIXME: This should really be done on the master select plan.
*/
if (!ExecSupportsBackwardScan(result->planTree))
{
FuncExpr *funcExpr = makeNode(FuncExpr);
TargetEntry *targetEntry = NULL;
bool resjunkAttribute = true;
funcExpr->funcretset = true;
targetEntry = makeTargetEntry((Expr *) funcExpr, InvalidAttrNumber, NULL,
resjunkAttribute);
fauxFunctionScan->scan.plan.targetlist =
lappend(fauxFunctionScan->scan.plan.targetlist,
targetEntry);
}
result->planTree = (Plan *) fauxFunctionScan;
return result;
}
/*
* PerformCursorOpen
* Execute SQL DECLARE CURSOR command.
*/
void
PerformCursorOpen(DeclareCursorStmt *stmt)
{
List *rewritten;
Query *query;
Plan *plan;
Portal portal;
MemoryContext oldContext;
/*
* Disallow empty-string cursor name (conflicts with protocol-level
* unnamed portal).
*/
if (!stmt->portalname || stmt->portalname[0] == '\0')
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_NAME),
errmsg("invalid cursor name: must not be empty")));
/*
* If this is a non-holdable cursor, we require that this statement
* has been executed inside a transaction block (or else, it would
* have no user-visible effect).
*/
if (!(stmt->options & CURSOR_OPT_HOLD))
RequireTransactionChain((void *) stmt, "DECLARE CURSOR");
/*
* Because the planner is not cool about not scribbling on its input,
* we make a preliminary copy of the source querytree. This prevents
* problems in the case that the DECLARE CURSOR is in a portal and is
* executed repeatedly. XXX the planner really shouldn't modify its
* input ... FIXME someday.
*/
query = copyObject(stmt->query);
/*
* The query has been through parse analysis, but not rewriting or
* planning as yet. Note that the grammar ensured we have a SELECT
* query, so we are not expecting rule rewriting to do anything
* strange.
*/
rewritten = QueryRewrite(query);
if (length(rewritten) != 1 || !IsA(lfirst(rewritten), Query))
elog(ERROR, "unexpected rewrite result");
query = (Query *) lfirst(rewritten);
if (query->commandType != CMD_SELECT)
elog(ERROR, "unexpected rewrite result");
if (query->into)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("DECLARE CURSOR may not specify INTO")));
if (query->rowMarks != NIL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("DECLARE CURSOR ... FOR UPDATE is not supported"),
errdetail("Cursors must be READ ONLY.")));
plan = planner(query, true, stmt->options);
/*
* Create a portal and copy the query and plan into its memory
* context.
*/
portal = CreatePortal(stmt->portalname, false, false);
oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
query = copyObject(query);
plan = copyObject(plan);
PortalDefineQuery(portal,
NULL, /* unfortunately don't have sourceText */
"SELECT", /* cursor's query is always a SELECT */
makeList1(query),
makeList1(plan),
PortalGetHeapMemory(portal));
MemoryContextSwitchTo(oldContext);
/*
* Set up options for portal.
*
* If the user didn't specify a SCROLL type, allow or disallow scrolling
* based on whether it would require any additional runtime overhead
* to do so.
*/
portal->cursorOptions = stmt->options;
if (!(portal->cursorOptions & (CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL)))
{
if (ExecSupportsBackwardScan(plan))
portal->cursorOptions |= CURSOR_OPT_SCROLL;
else
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
}
/*
* Start execution --- never any params for a cursor.
*/
PortalStart(portal, NULL);
Assert(portal->strategy == PORTAL_ONE_SELECT);
/*
* We're done; the query won't actually be run until
* PerformPortalFetch is called.
*/
}