greenplumn tlist 源码
greenplumn tlist 代码
文件路径：/src/backend/optimizer/util/tlist.c
/*-------------------------------------------------------------------------
*
* tlist.c
* Target list manipulation routines
*
* Portions Copyright (c) 2007-2008, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/util/tlist.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/cost.h"
#include "optimizer/optimizer.h"
#include "optimizer/tlist.h"
#include "utils/lsyscache.h" /* get_typavgwidth() */
typedef struct maxSortGroupRef_context
{
Index maxsgr;
bool include_orderedagg;
} maxSortGroupRef_context;
static
bool maxSortGroupRef_walker(Node *node, maxSortGroupRef_context *cxt);
/* Test if an expression node represents a SRF call. Beware multiple eval! */
#define IS_SRF_CALL(node) \
((IsA(node, FuncExpr) && ((FuncExpr *) (node))->funcretset) || \
(IsA(node, OpExpr) && ((OpExpr *) (node))->opretset))
/*
* Data structures for split_pathtarget_at_srfs(). To preserve the identity
* of sortgroupref items even if they are textually equal(), what we track is
* not just bare expressions but expressions plus their sortgroupref indexes.
*/
typedef struct
{
Node *expr; /* some subexpression of a PathTarget */
Index sortgroupref; /* its sortgroupref, or 0 if none */
} split_pathtarget_item;
typedef struct
{
/* This is a List of bare expressions: */
List *input_target_exprs; /* exprs available from input */
/* These are Lists of Lists of split_pathtarget_items: */
List *level_srfs; /* SRF exprs to evaluate at each level */
List *level_input_vars; /* input vars needed at each level */
List *level_input_srfs; /* input SRFs needed at each level */
/* These are Lists of split_pathtarget_items: */
List *current_input_vars; /* vars needed in current subexpr */
List *current_input_srfs; /* SRFs needed in current subexpr */
/* Auxiliary data for current split_pathtarget_walker traversal: */
int current_depth; /* max SRF depth in current subexpr */
Index current_sgref; /* current subexpr's sortgroupref, or 0 */
} split_pathtarget_context;
static bool split_pathtarget_walker(Node *node,
split_pathtarget_context *context);
static void add_sp_item_to_pathtarget(PathTarget *target,
split_pathtarget_item *item);
static void add_sp_items_to_pathtarget(PathTarget *target, List *items);
/*****************************************************************************
* Target list creation and searching utilities
*****************************************************************************/
/*
* tlist_member
* Finds the (first) member of the given tlist whose expression is
* equal() to the given expression. Result is NULL if no such member.
*/
TargetEntry *
tlist_member(Expr *node, List *targetlist)
{
ListCell *temp;
foreach(temp, targetlist)
{
TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
Assert(IsA(tlentry, TargetEntry));
if (equal(node, tlentry->expr))
return tlentry;
}
return NULL;
}
/*
* tlist_members
* Finds all members of the given tlist whose expression is
* equal() to the given expression. Result is NIL if no such member.
* Note: We do not make a copy of the tlist entries that match.
* The caller is responsible for cleaning up the memory allocated
* to the List returned.
*/
List *
tlist_members(Node *node, List *targetlist)
{
List *tlist = NIL;
ListCell *temp = NULL;
foreach(temp, targetlist)
{
TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
Assert(IsA(tlentry, TargetEntry));
if (equal(node, tlentry->expr))
{
tlist = lappend(tlist, tlentry);
}
}
return tlist;
}
/*
* tlist_member_ignore_relabel
* Same as above, except that we ignore top-level RelabelType nodes
* while checking for a match. This is needed for some scenarios
* involving binary-compatible sort operations.
*/
TargetEntry *
tlist_member_ignore_relabel(Expr *node, List *targetlist)
{
ListCell *temp;
while (node && IsA(node, RelabelType))
node = ((RelabelType *) node)->arg;
foreach(temp, targetlist)
{
TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
Expr *tlexpr = tlentry->expr;
while (tlexpr && IsA(tlexpr, RelabelType))
tlexpr = ((RelabelType *) tlexpr)->arg;
if (equal(node, tlexpr))
return tlentry;
}
return NULL;
}
/*
* tlist_member_match_var
* Same as above, except that we match the provided Var on the basis
* of varno/varattno/varlevelsup/vartype only, rather than full equal().
*
* This is needed in some cases where we can't be sure of an exact typmod
* match. For safety, though, we insist on vartype match.
*/
static TargetEntry *
tlist_member_match_var(Var *var, List *targetlist)
{
ListCell *temp;
foreach(temp, targetlist)
{
TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
Var *tlvar = (Var *) tlentry->expr;
if (!tlvar || !IsA(tlvar, Var))
continue;
if (var->varno == tlvar->varno &&
var->varattno == tlvar->varattno &&
var->varlevelsup == tlvar->varlevelsup &&
var->vartype == tlvar->vartype)
return tlentry;
}
return NULL;
}
/*
* add_to_flat_tlist
* Add more items to a flattened tlist (if they're not already in it)
*
* 'tlist' is the flattened tlist
* 'exprs' is a list of expressions (usually, but not necessarily, Vars)
*
* Returns the extended tlist.
*/
List *
add_to_flat_tlist(List *tlist, List *exprs)
{
int next_resno = list_length(tlist) + 1;
ListCell *lc;
foreach(lc, exprs)
{
Expr *expr = (Expr *) lfirst(lc);
if (!tlist_member_ignore_relabel(expr, tlist))
{
TargetEntry *tle;
tle = makeTargetEntry(copyObject(expr), /* copy needed?? */
next_resno++,
NULL,
false);
tlist = lappend(tlist, tle);
}
}
return tlist;
}
/*
* get_tlist_exprs
* Get just the expression subtrees of a tlist
*
* Resjunk columns are ignored unless includeJunk is true
*/
List *
get_tlist_exprs(List *tlist, bool includeJunk)
{
List *result = NIL;
ListCell *l;
foreach(l, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resjunk && !includeJunk)
continue;
result = lappend(result, tle->expr);
}
return result;
}
/*
* count_nonjunk_tlist_entries
* What it says ...
*/
int
count_nonjunk_tlist_entries(List *tlist)
{
int len = 0;
ListCell *l;
foreach(l, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (!tle->resjunk)
len++;
}
return len;
}
/*
* tlist_same_exprs
* Check whether two target lists contain the same expressions
*
* Note: this function is used to decide whether it's safe to jam a new tlist
* into a non-projection-capable plan node. Obviously we can't do that unless
* the node's tlist shows it already returns the column values we want.
* However, we can ignore the TargetEntry attributes resname, ressortgroupref,
* resorigtbl, resorigcol, and resjunk, because those are only labelings that
* don't affect the row values computed by the node. (Moreover, if we didn't
* ignore them, we'd frequently fail to make the desired optimization, since
* the planner tends to not bother to make resname etc. valid in intermediate
* plan nodes.) Note that on success, the caller must still jam the desired
* tlist into the plan node, else it won't have the desired labeling fields.
*/
bool
tlist_same_exprs(List *tlist1, List *tlist2)
{
ListCell *lc1,
*lc2;
if (list_length(tlist1) != list_length(tlist2))
return false; /* not same length, so can't match */
forboth(lc1, tlist1, lc2, tlist2)
{
TargetEntry *tle1 = (TargetEntry *) lfirst(lc1);
TargetEntry *tle2 = (TargetEntry *) lfirst(lc2);
if (!equal(tle1->expr, tle2->expr))
return false;
}
return true;
}
/*
* Does tlist have same output datatypes as listed in colTypes?
*
* Resjunk columns are ignored if junkOK is true; otherwise presence of
* a resjunk column will always cause a 'false' result.
*
* Note: currently no callers care about comparing typmods.
*/
bool
tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK)
{
ListCell *l;
ListCell *curColType = list_head(colTypes);
foreach(l, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resjunk)
{
if (!junkOK)
return false;
}
else
{
if (curColType == NULL)
return false; /* tlist longer than colTypes */
if (exprType((Node *) tle->expr) != lfirst_oid(curColType))
return false;
curColType = lnext(curColType);
}
}
if (curColType != NULL)
return false; /* tlist shorter than colTypes */
return true;
}
/*
* Does tlist have same exposed collations as listed in colCollations?
*
* Identical logic to the above, but for collations.
*/
bool
tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
{
ListCell *l;
ListCell *curColColl = list_head(colCollations);
foreach(l, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resjunk)
{
if (!junkOK)
return false;
}
else
{
if (curColColl == NULL)
return false; /* tlist longer than colCollations */
if (exprCollation((Node *) tle->expr) != lfirst_oid(curColColl))
return false;
curColColl = lnext(curColColl);
}
}
if (curColColl != NULL)
return false; /* tlist shorter than colCollations */
return true;
}
/*
* apply_tlist_labeling
* Apply the TargetEntry labeling attributes of src_tlist to dest_tlist
*
* This is useful for reattaching column names etc to a plan's final output
* targetlist.
*/
void
apply_tlist_labeling(List *dest_tlist, List *src_tlist)
{
ListCell *ld,
*ls;
Assert(list_length(dest_tlist) == list_length(src_tlist));
forboth(ld, dest_tlist, ls, src_tlist)
{
TargetEntry *dest_tle = (TargetEntry *) lfirst(ld);
TargetEntry *src_tle = (TargetEntry *) lfirst(ls);
Assert(dest_tle->resno == src_tle->resno);
dest_tle->resname = src_tle->resname;
dest_tle->ressortgroupref = src_tle->ressortgroupref;
dest_tle->resorigtbl = src_tle->resorigtbl;
dest_tle->resorigcol = src_tle->resorigcol;
dest_tle->resjunk = src_tle->resjunk;
}
}
/*
* get_sortgroupref_tle
* Find the targetlist entry matching the given SortGroupRef index,
* and return it.
*/
TargetEntry *
get_sortgroupref_tle(Index sortref, List *targetList)
{
ListCell *l;
foreach(l, targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->ressortgroupref == sortref)
return tle;
}
elog(ERROR, "ORDER/GROUP BY expression not found in targetlist");
return NULL; /* keep compiler quiet */
}
/*
* get_sortgroupclause_tle
* Find the targetlist entry matching the given SortGroupClause
* by ressortgroupref, and return it.
*/
TargetEntry *
get_sortgroupclause_tle(SortGroupClause *sgClause,
List *targetList)
{
return get_sortgroupref_tle(sgClause->tleSortGroupRef, targetList);
}
/*
* get_sortgroupclauses_tles
* Find a list of unique targetlist entries matching the given list of
* SortGroupClauses, or GroupingClauses.
*
* In each grouping set, targets that do not appear in a GroupingClause
* will be put in the front of those that appear in a GroupingClauses.
* The targets within the same clause will be appended in the order
* of their appearance.
*
* The unique targetlist entries are returned in *tles, and the sort
* and equality operators associated with each tle are returned in
* *sortops and *eqops.
*/
static void
get_sortgroupclauses_tles_recurse(List *clauses, List *targetList,
List **tles, List **sortops, List **eqops)
{
ListCell *lc;
ListCell *lc_sortop;
ListCell *lc_eqop;
List *sub_grouping_tles = NIL;
List *sub_grouping_sortops = NIL;
List *sub_grouping_eqops = NIL;
foreach(lc, clauses)
{
Node *node = lfirst(lc);
if (node == NULL)
continue;
if (IsA(node, SortGroupClause))
{
SortGroupClause *sgc = (SortGroupClause *) node;
TargetEntry *tle = get_sortgroupclause_tle(sgc,
targetList);
if (!list_member(*tles, tle))
{
*tles = lappend(*tles, tle);
*sortops = lappend_oid(*sortops, sgc->sortop);
*eqops = lappend_oid(*eqops, sgc->eqop);
}
}
else if (IsA(node, List))
{
get_sortgroupclauses_tles_recurse((List *) node, targetList,
tles, sortops, eqops);
}
else
elog(ERROR, "unrecognized node type in list of sort/group clauses: %d",
(int) nodeTag(node));
}
/*
* Put SortGroupClauses before GroupingClauses.
*/
forthree(lc, sub_grouping_tles,
lc_sortop, sub_grouping_sortops,
lc_eqop, sub_grouping_eqops)
{
if (!list_member(*tles, lfirst(lc)))
{
*tles = lappend(*tles, lfirst(lc));
*sortops = lappend_oid(*sortops, lfirst_oid(lc_sortop));
*eqops = lappend_oid(*eqops, lfirst_oid(lc_eqop));
}
}
}
void
get_sortgroupclauses_tles(List *clauses, List *targetList,
List **tles, List **sortops, List **eqops)
{
*tles = NIL;
*sortops = NIL;
*eqops = NIL;
get_sortgroupclauses_tles_recurse(clauses, targetList,
tles, sortops, eqops);
}
/*
* get_sortgroupclause_expr
* Find the targetlist entry matching the given SortGroupClause
* by ressortgroupref, and return its expression.
*/
Node *
get_sortgroupclause_expr(SortGroupClause *sgClause, List *targetList)
{
TargetEntry *tle = get_sortgroupclause_tle(sgClause, targetList);
return (Node *) tle->expr;
}
/*
* get_sortgrouplist_exprs
* Given a list of SortGroupClauses, build a list
* of the referenced targetlist expressions.
*/
List *
get_sortgrouplist_exprs(List *sgClauses, List *targetList)
{
List *result = NIL;
ListCell *l;
foreach(l, sgClauses)
{
SortGroupClause *sortcl = (SortGroupClause *) lfirst(l);
Node *sortexpr;
sortexpr = get_sortgroupclause_expr(sortcl, targetList);
result = lappend(result, sortexpr);
}
return result;
}
/*
* get_sortgroupref_clause
* Find the SortGroupClause matching the given SortGroupRef index,
* and return it.
*/
SortGroupClause *
get_sortgroupref_clause(Index sortref, List *clauses)
{
ListCell *l;
foreach(l, clauses)
{
SortGroupClause *cl = (SortGroupClause *) lfirst(l);
if (cl->tleSortGroupRef == sortref)
return cl;
}
elog(ERROR, "ORDER/GROUP BY expression not found in list");
return NULL; /* keep compiler quiet */
}
/*
* get_sortgroupref_clause_noerr
* As above, but return NULL rather than throwing an error if not found.
*/
SortGroupClause *
get_sortgroupref_clause_noerr(Index sortref, List *clauses)
{
ListCell *l;
foreach(l, clauses)
{
SortGroupClause *cl = (SortGroupClause *) lfirst(l);
if (cl->tleSortGroupRef == sortref)
return cl;
}
return NULL;
}
/*
* extract_grouping_ops - make an array of the equality operator OIDs
* for a SortGroupClause list
*/
Oid *
extract_grouping_ops(List *groupClause)
{
int numCols = list_length(groupClause);
int colno = 0;
Oid *groupOperators;
ListCell *glitem;
groupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
foreach(glitem, groupClause)
{
SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
groupOperators[colno] = groupcl->eqop;
Assert(OidIsValid(groupOperators[colno]));
colno++;
}
return groupOperators;
}
/*
* extract_grouping_collations - make an array of the grouping column collations
* for a SortGroupClause list
*/
Oid *
extract_grouping_collations(List *groupClause, List *tlist)
{
int numCols = list_length(groupClause);
int colno = 0;
Oid *grpCollations;
ListCell *glitem;
grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
foreach(glitem, groupClause)
{
SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
grpCollations[colno++] = exprCollation((Node *) tle->expr);
}
return grpCollations;
}
/*
* extract_grouping_cols - make an array of the grouping column resnos
* for a SortGroupClause list
*/
AttrNumber *
extract_grouping_cols(List *groupClause, List *tlist)
{
AttrNumber *grpColIdx;
int numCols = list_length(groupClause);
int colno = 0;
ListCell *glitem;
grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
foreach(glitem, groupClause)
{
SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
grpColIdx[colno++] = tle->resno;
}
return grpColIdx;
}
/*
* grouping_is_sortable - is it possible to implement grouping list by sorting?
*
* This is easy since the parser will have included a sortop if one exists.
*/
bool
grouping_is_sortable(List *groupClause)
{
ListCell *glitem;
foreach(glitem, groupClause)
{
SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
if (!OidIsValid(groupcl->sortop))
return false;
}
return true;
}
/*
* grouping_is_hashable - is it possible to implement grouping list by hashing?
*
* We rely on the parser to have set the hashable flag correctly.
*/
bool
grouping_is_hashable(List *groupClause)
{
ListCell *glitem;
foreach(glitem, groupClause)
{
SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
if (!groupcl->hashable)
return false;
}
return true;
}
/*
* Return the largest sortgroupref value in use in the given
* target list.
*
* If include_orderedagg is false, consider only the top-level
* entries in the target list, i.e., those that might be occur
* in a groupClause, distinctClause, or sortClause of the Query
* node that immediately contains the target list.
*
* If include_orderedagg is true, also consider AggOrder entries
* embedded in Aggref nodes within the target list. Though
* such entries will only occur in the aggregation sub_tlist
* (input) they affect sortgroupref numbering for both sub_tlist
* and tlist (aggregate).
*/
Index maxSortGroupRef(List *targetlist, bool include_orderedagg)
{
maxSortGroupRef_context context;
context.maxsgr = 0;
context.include_orderedagg = include_orderedagg;
if (targetlist != NIL)
{
if ( !IsA(targetlist, List) || !IsA(linitial(targetlist), TargetEntry ) )
elog(ERROR, "non-targetlist argument supplied");
maxSortGroupRef_walker((Node*)targetlist, &context);
}
return context.maxsgr;
}
bool maxSortGroupRef_walker(Node *node, maxSortGroupRef_context *cxt)
{
if ( node == NULL )
return false;
if ( IsA(node, TargetEntry) )
{
TargetEntry *tle = (TargetEntry*)node;
if ( tle->ressortgroupref > cxt->maxsgr )
cxt->maxsgr = tle->ressortgroupref;
return maxSortGroupRef_walker((Node*)tle->expr, cxt);
}
/* Aggref nodes don't nest, so we can treat them here without recurring
* further.
*/
if ( IsA(node, Aggref) )
{
Aggref *ref = (Aggref*)node;
if ( cxt->include_orderedagg )
{
ListCell *lc;
foreach (lc, ref->aggorder)
{
SortGroupClause *sort = (SortGroupClause *)lfirst(lc);
Assert(IsA(sort, SortGroupClause));
Assert( sort->tleSortGroupRef != 0 );
if (sort->tleSortGroupRef > cxt->maxsgr )
cxt->maxsgr = sort->tleSortGroupRef;
}
}
return false;
}
return expression_tree_walker(node, maxSortGroupRef_walker, cxt);
}
/**
* Returns the width of the row by traversing through the
* target list and adding up the width of each target entry.
*/
int get_row_width(List *tlist)
{
int width = 0;
ListCell *plc = NULL;
foreach(plc, tlist)
{
TargetEntry *pte = (TargetEntry*) lfirst(plc);
Expr *pexpr = pte->expr;
Assert(NULL != pexpr);
Oid oidType = exprType( (Node *) pexpr);
int32 iTypmod = exprTypmod( (Node *) pexpr);
width += get_typavgwidth(oidType, iTypmod);
}
return width;
}
/*****************************************************************************
* PathTarget manipulation functions
*
* PathTarget is a somewhat stripped-down version of a full targetlist; it
* omits all the TargetEntry decoration except (optionally) sortgroupref data,
* and it adds evaluation cost and output data width info.
*****************************************************************************/
/*
* make_pathtarget_from_tlist
* Construct a PathTarget equivalent to the given targetlist.
*
* This leaves the cost and width fields as zeroes. Most callers will want
* to use create_pathtarget(), so as to get those set.
*/
PathTarget *
make_pathtarget_from_tlist(List *tlist)
{
PathTarget *target = makeNode(PathTarget);
int i;
ListCell *lc;
target->sortgrouprefs = (Index *) palloc(list_length(tlist) * sizeof(Index));
i = 0;
foreach(lc, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
target->exprs = lappend(target->exprs, tle->expr);
target->sortgrouprefs[i] = tle->ressortgroupref;
i++;
}
return target;
}
/*
* make_tlist_from_pathtarget
* Construct a targetlist from a PathTarget.
*/
List *
make_tlist_from_pathtarget(PathTarget *target)
{
List *tlist = NIL;
int i;
ListCell *lc;
i = 0;
foreach(lc, target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
TargetEntry *tle;
tle = makeTargetEntry(expr,
i + 1,
NULL,
false);
if (target->sortgrouprefs)
tle->ressortgroupref = target->sortgrouprefs[i];
tlist = lappend(tlist, tle);
i++;
}
return tlist;
}
/*
* copy_pathtarget
* Copy a PathTarget.
*
* The new PathTarget has its own List cells, but shares the underlying
* target expression trees with the old one. We duplicate the List cells
* so that items can be added to one target without damaging the other.
*/
PathTarget *
copy_pathtarget(PathTarget *src)
{
PathTarget *dst = makeNode(PathTarget);
/* Copy scalar fields */
memcpy(dst, src, sizeof(PathTarget));
/* Shallow-copy the expression list */
dst->exprs = list_copy(src->exprs);
/* Duplicate sortgrouprefs if any (if not, the memcpy handled this) */
if (src->sortgrouprefs)
{
Size nbytes = list_length(src->exprs) * sizeof(Index);
dst->sortgrouprefs = (Index *) palloc(nbytes);
memcpy(dst->sortgrouprefs, src->sortgrouprefs, nbytes);
}
return dst;
}
/*
* create_empty_pathtarget
* Create an empty (zero columns, zero cost) PathTarget.
*/
PathTarget *
create_empty_pathtarget(void)
{
/* This is easy, but we don't want callers to hard-wire this ... */
return makeNode(PathTarget);
}
/*
* add_column_to_pathtarget
* Append a target column to the PathTarget.
*
* As with make_pathtarget_from_tlist, we leave it to the caller to update
* the cost and width fields.
*/
void
add_column_to_pathtarget(PathTarget *target, Expr *expr, Index sortgroupref)
{
/* Updating the exprs list is easy ... */
target->exprs = lappend(target->exprs, expr);
/* ... the sortgroupref data, a bit less so */
if (target->sortgrouprefs)
{
int nexprs = list_length(target->exprs);
/* This might look inefficient, but actually it's usually cheap */
target->sortgrouprefs = (Index *)
repalloc(target->sortgrouprefs, nexprs * sizeof(Index));
target->sortgrouprefs[nexprs - 1] = sortgroupref;
}
else if (sortgroupref)
{
/* Adding sortgroupref labeling to a previously unlabeled target */
int nexprs = list_length(target->exprs);
target->sortgrouprefs = (Index *) palloc0(nexprs * sizeof(Index));
target->sortgrouprefs[nexprs - 1] = sortgroupref;
}
}
/*
* add_new_column_to_pathtarget
* Append a target column to the PathTarget, but only if it's not
* equal() to any pre-existing target expression.
*
* The caller cannot specify a sortgroupref, since it would be unclear how
* to merge that with a pre-existing column.
*
* As with make_pathtarget_from_tlist, we leave it to the caller to update
* the cost and width fields.
*/
void
add_new_column_to_pathtarget(PathTarget *target, Expr *expr)
{
if (!list_member(target->exprs, expr))
add_column_to_pathtarget(target, expr, 0);
}
/*
* add_new_columns_to_pathtarget
* Apply add_new_column_to_pathtarget() for each element of the list.
*/
void
add_new_columns_to_pathtarget(PathTarget *target, List *exprs)
{
ListCell *lc;
foreach(lc, exprs)
{
Expr *expr = (Expr *) lfirst(lc);
add_new_column_to_pathtarget(target, expr);
}
}
/*
* apply_pathtarget_labeling_to_tlist
* Apply any sortgrouprefs in the PathTarget to matching tlist entries
*
* Here, we do not assume that the tlist entries are one-for-one with the
* PathTarget. The intended use of this function is to deal with cases
* where createplan.c has decided to use some other tlist and we have
* to identify what matches exist.
*/
void
apply_pathtarget_labeling_to_tlist(List *tlist, PathTarget *target)
{
int i;
ListCell *lc;
/* Nothing to do if PathTarget has no sortgrouprefs data */
if (target->sortgrouprefs == NULL)
return;
i = 0;
foreach(lc, target->exprs)
{
Expr *expr = (Expr *) lfirst(lc);
TargetEntry *tle;
if (target->sortgrouprefs[i])
{
/*
* For Vars, use tlist_member_match_var's weakened matching rule;
* this allows us to deal with some cases where a set-returning
* function has been inlined, so that we now have more knowledge
* about what it returns than we did when the original Var was
* created. Otherwise, use regular equal() to find the matching
* TLE. (In current usage, only the Var case is actually needed;
* but it seems best to have sane behavior here for non-Vars too.)
*/
if (expr && IsA(expr, Var))
tle = tlist_member_match_var((Var *) expr, tlist);
else
tle = tlist_member(expr, tlist);
/*
* Complain if noplace for the sortgrouprefs label, or if we'd
* have to label a column twice. (The case where it already has
* the desired label probably can't happen, but we may as well
* allow for it.)
*/
if (!tle)
elog(ERROR, "ORDER/GROUP BY expression not found in targetlist");
if (tle->ressortgroupref != 0 &&
tle->ressortgroupref != target->sortgrouprefs[i])
elog(ERROR, "targetlist item has multiple sortgroupref labels");
tle->ressortgroupref = target->sortgrouprefs[i];
}
i++;
}
}
/*
* split_pathtarget_at_srfs
* Split given PathTarget into multiple levels to position SRFs safely
*
* The executor can only handle set-returning functions that appear at the
* top level of the targetlist of a ProjectSet plan node. If we have any SRFs
* that are not at top level, we need to split up the evaluation into multiple
* plan levels in which each level satisfies this constraint. This function
* creates appropriate PathTarget(s) for each level.
*
* As an example, consider the tlist expression
* x + srf1(srf2(y + z))
* This expression should appear as-is in the top PathTarget, but below that
* we must have a PathTarget containing
* x, srf1(srf2(y + z))
* and below that, another PathTarget containing
* x, srf2(y + z)
* and below that, another PathTarget containing
* x, y, z
* When these tlists are processed by setrefs.c, subexpressions that match
* output expressions of the next lower tlist will be replaced by Vars,
* so that what the executor gets are tlists looking like
* Var1 + Var2
* Var1, srf1(Var2)
* Var1, srf2(Var2 + Var3)
* x, y, z
* which satisfy the desired property.
*
* Another example is
* srf1(x), srf2(srf3(y))
* That must appear as-is in the top PathTarget, but below that we need
* srf1(x), srf3(y)
* That is, each SRF must be computed at a level corresponding to the nesting
* depth of SRFs within its arguments.
*
* In some cases, a SRF has already been evaluated in some previous plan level
* and we shouldn't expand it again (that is, what we see in the target is
* already meant as a reference to a lower subexpression). So, don't expand
* any tlist expressions that appear in input_target, if that's not NULL.
*
* It's also important that we preserve any sortgroupref annotation appearing
* in the given target, especially on expressions matching input_target items.
*
* The outputs of this function are two parallel lists, one a list of
* PathTargets and the other an integer list of bool flags indicating
* whether the corresponding PathTarget contains any evaluatable SRFs.
* The lists are given in the order they'd need to be evaluated in, with
* the "lowest" PathTarget first. So the last list entry is always the
* originally given PathTarget, and any entries before it indicate evaluation
* levels that must be inserted below it. The first list entry must not
* contain any SRFs (other than ones duplicating input_target entries), since
* it will typically be attached to a plan node that cannot evaluate SRFs.
*
* Note: using a list for the flags may seem like overkill, since there
* are only a few possible patterns for which levels contain SRFs.
* But this representation decouples callers from that knowledge.
*/
void
split_pathtarget_at_srfs(PlannerInfo *root,
PathTarget *target, PathTarget *input_target,
List **targets, List **targets_contain_srfs)
{
split_pathtarget_context context;
int max_depth;
bool need_extra_projection;
List *prev_level_tlist;
int lci;
ListCell *lc,
*lc1,
*lc2,
*lc3;
/*
* It's not unusual for planner.c to pass us two physically identical
* targets, in which case we can conclude without further ado that all
* expressions are available from the input. (The logic below would
* arrive at the same conclusion, but much more tediously.)
*/
if (target == input_target)
{
*targets = list_make1(target);
*targets_contain_srfs = list_make1_int(false);
return;
}
/* Pass any input_target exprs down to split_pathtarget_walker() */
context.input_target_exprs = input_target ? input_target->exprs : NIL;
/*
* Initialize with empty level-zero lists, and no levels after that.
* (Note: we could dispense with representing level zero explicitly, since
* it will never receive any SRFs, but then we'd have to special-case that
* level when we get to building result PathTargets. Level zero describes
* the SRF-free PathTarget that will be given to the input plan node.)
*/
context.level_srfs = list_make1(NIL);
context.level_input_vars = list_make1(NIL);
context.level_input_srfs = list_make1(NIL);
/* Initialize data we'll accumulate across all the target expressions */
context.current_input_vars = NIL;
context.current_input_srfs = NIL;
max_depth = 0;
need_extra_projection = false;
/* Scan each expression in the PathTarget looking for SRFs */
lci = 0;
foreach(lc, target->exprs)
{
Node *node = (Node *) lfirst(lc);
/* Tell split_pathtarget_walker about this expr's sortgroupref */
context.current_sgref = get_pathtarget_sortgroupref(target, lci);
lci++;
/*
* Find all SRFs and Vars (and Var-like nodes) in this expression, and
* enter them into appropriate lists within the context struct.
*/
context.current_depth = 0;
split_pathtarget_walker(node, &context);
/* An expression containing no SRFs is of no further interest */
if (context.current_depth == 0)
continue;
/*
* Track max SRF nesting depth over the whole PathTarget. Also, if
* this expression establishes a new max depth, we no longer care
* whether previous expressions contained nested SRFs; we can handle
* any required projection for them in the final ProjectSet node.
*/
if (max_depth < context.current_depth)
{
max_depth = context.current_depth;
need_extra_projection = false;
}
/*
* If any maximum-depth SRF is not at the top level of its expression,
* we'll need an extra Result node to compute the top-level scalar
* expression.
*/
if (max_depth == context.current_depth && !IS_SRF_CALL(node))
need_extra_projection = true;
}
/*
* If we found no SRFs needing evaluation (maybe they were all present in
* input_target, or maybe they were all removed by const-simplification),
* then no ProjectSet is needed; fall out.
*/
if (max_depth == 0)
{
*targets = list_make1(target);
*targets_contain_srfs = list_make1_int(false);
return;
}
/*
* The Vars and SRF outputs needed at top level can be added to the last
* level_input lists if we don't need an extra projection step. If we do
* need one, add a SRF-free level to the lists.
*/
if (need_extra_projection)
{
context.level_srfs = lappend(context.level_srfs, NIL);
context.level_input_vars = lappend(context.level_input_vars,
context.current_input_vars);
context.level_input_srfs = lappend(context.level_input_srfs,
context.current_input_srfs);
}
else
{
lc = list_nth_cell(context.level_input_vars, max_depth);
lfirst(lc) = list_concat(lfirst(lc), context.current_input_vars);
lc = list_nth_cell(context.level_input_srfs, max_depth);
lfirst(lc) = list_concat(lfirst(lc), context.current_input_srfs);
}
/*
* Now construct the output PathTargets. The original target can be used
* as-is for the last one, but we need to construct a new SRF-free target
* representing what the preceding plan node has to emit, as well as a
* target for each intermediate ProjectSet node.
*/
*targets = *targets_contain_srfs = NIL;
prev_level_tlist = NIL;
forthree(lc1, context.level_srfs,
lc2, context.level_input_vars,
lc3, context.level_input_srfs)
{
List *level_srfs = (List *) lfirst(lc1);
PathTarget *ntarget;
if (lnext(lc1) == NULL)
{
ntarget = target;
}
else
{
ntarget = create_empty_pathtarget();
/*
* This target should actually evaluate any SRFs of the current
* level, and it needs to propagate forward any Vars needed by
* later levels, as well as SRFs computed earlier and needed by
* later levels.
*/
add_sp_items_to_pathtarget(ntarget, level_srfs);
for_each_cell(lc, lnext(lc2))
{
List *input_vars = (List *) lfirst(lc);
add_sp_items_to_pathtarget(ntarget, input_vars);
}
for_each_cell(lc, lnext(lc3))
{
List *input_srfs = (List *) lfirst(lc);
ListCell *lcx;
foreach(lcx, input_srfs)
{
split_pathtarget_item *item = lfirst(lcx);
if (list_member(prev_level_tlist, item->expr))
add_sp_item_to_pathtarget(ntarget, item);
}
}
set_pathtarget_cost_width(root, ntarget);
}
/*
* Add current target and does-it-compute-SRFs flag to output lists.
*/
*targets = lappend(*targets, ntarget);
*targets_contain_srfs = lappend_int(*targets_contain_srfs,
(level_srfs != NIL));
/* Remember this level's output for next pass */
prev_level_tlist = ntarget->exprs;
}
}
/*
* Recursively examine expressions for split_pathtarget_at_srfs.
*
* Note we make no effort here to prevent duplicate entries in the output
* lists. Duplicates will be gotten rid of later.
*/
static bool
split_pathtarget_walker(Node *node, split_pathtarget_context *context)
{
if (node == NULL)
return false;
/*
* A subexpression that matches an expression already computed in
* input_target can be treated like a Var (which indeed it will be after
* setrefs.c gets done with it), even if it's actually a SRF. Record it
* as being needed for the current expression, and ignore any
* substructure. (Note in particular that this preserves the identity of
* any expressions that appear as sortgrouprefs in input_target.)
*/
if (list_member(context->input_target_exprs, node))
{
split_pathtarget_item *item = palloc(sizeof(split_pathtarget_item));
item->expr = node;
item->sortgroupref = context->current_sgref;
context->current_input_vars = lappend(context->current_input_vars,
item);
return false;
}
/*
* Vars and Var-like constructs are expected to be gotten from the input,
* too. We assume that these constructs cannot contain any SRFs (if one
* does, there will be an executor failure from a misplaced SRF).
*/
if (IsA(node, Var) ||
IsA(node, PlaceHolderVar) ||
IsA(node, Aggref) ||
IsA(node, GroupingFunc) ||
IsA(node, WindowFunc))
{
split_pathtarget_item *item = palloc(sizeof(split_pathtarget_item));
item->expr = node;
item->sortgroupref = context->current_sgref;
context->current_input_vars = lappend(context->current_input_vars,
item);
return false;
}
/*
* If it's a SRF, recursively examine its inputs, determine its level, and
* make appropriate entries in the output lists.
*/
if (IS_SRF_CALL(node))
{
split_pathtarget_item *item = palloc(sizeof(split_pathtarget_item));
List *save_input_vars = context->current_input_vars;
List *save_input_srfs = context->current_input_srfs;
int save_current_depth = context->current_depth;
int srf_depth;
ListCell *lc;
item->expr = node;
item->sortgroupref = context->current_sgref;
context->current_input_vars = NIL;
context->current_input_srfs = NIL;
context->current_depth = 0;
context->current_sgref = 0; /* subexpressions are not sortgroup items */
(void) expression_tree_walker(node, split_pathtarget_walker,
(void *) context);
/* Depth is one more than any SRF below it */
srf_depth = context->current_depth + 1;
/* If new record depth, initialize another level of output lists */
if (srf_depth >= list_length(context->level_srfs))
{
context->level_srfs = lappend(context->level_srfs, NIL);
context->level_input_vars = lappend(context->level_input_vars, NIL);
context->level_input_srfs = lappend(context->level_input_srfs, NIL);
}
/* Record this SRF as needing to be evaluated at appropriate level */
lc = list_nth_cell(context->level_srfs, srf_depth);
lfirst(lc) = lappend(lfirst(lc), item);
/* Record its inputs as being needed at the same level */
lc = list_nth_cell(context->level_input_vars, srf_depth);
lfirst(lc) = list_concat(lfirst(lc), context->current_input_vars);
lc = list_nth_cell(context->level_input_srfs, srf_depth);
lfirst(lc) = list_concat(lfirst(lc), context->current_input_srfs);
/*
* Restore caller-level state and update it for presence of this SRF.
* Notice we report the SRF itself as being needed for evaluation of
* surrounding expression.
*/
context->current_input_vars = save_input_vars;
context->current_input_srfs = lappend(save_input_srfs, item);
context->current_depth = Max(save_current_depth, srf_depth);
/* We're done here */
return false;
}
/*
* Otherwise, the node is a scalar (non-set) expression, so recurse to
* examine its inputs.
*/
context->current_sgref = 0; /* subexpressions are not sortgroup items */
return expression_tree_walker(node, split_pathtarget_walker,
(void *) context);
}
/*
* Add a split_pathtarget_item to the PathTarget, unless a matching item is
* already present. This is like add_new_column_to_pathtarget, but allows
* for sortgrouprefs to be handled. An item having zero sortgroupref can
* be merged with one that has a sortgroupref, acquiring the latter's
* sortgroupref.
*
* Note that we don't worry about possibly adding duplicate sortgrouprefs
* to the PathTarget. That would be bad, but it should be impossible unless
* the target passed to split_pathtarget_at_srfs already had duplicates.
* As long as it didn't, we can have at most one split_pathtarget_item with
* any particular nonzero sortgroupref.
*/
static void
add_sp_item_to_pathtarget(PathTarget *target, split_pathtarget_item *item)
{
int lci;
ListCell *lc;
/*
* Look for a pre-existing entry that is equal() and does not have a
* conflicting sortgroupref already.
*/
lci = 0;
foreach(lc, target->exprs)
{
Node *node = (Node *) lfirst(lc);
Index sgref = get_pathtarget_sortgroupref(target, lci);
if ((item->sortgroupref == sgref ||
item->sortgroupref == 0 ||
sgref == 0) &&
equal(item->expr, node))
{
/* Found a match. Assign item's sortgroupref if it has one. */
if (item->sortgroupref)
{
if (target->sortgrouprefs == NULL)
{
target->sortgrouprefs = (Index *)
palloc0(list_length(target->exprs) * sizeof(Index));
}
target->sortgrouprefs[lci] = item->sortgroupref;
}
return;
}
lci++;
}
/*
* No match, so add item to PathTarget. Copy the expr for safety.
*/
add_column_to_pathtarget(target, (Expr *) copyObject(item->expr),
item->sortgroupref);
}
/*
* Apply add_sp_item_to_pathtarget to each element of list.
*/
static void
add_sp_items_to_pathtarget(PathTarget *target, List *items)
{
ListCell *lc;
foreach(lc, items)
{
split_pathtarget_item *item = lfirst(lc);
add_sp_item_to_pathtarget(target, item);
}
}
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