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SEARCH and CYCLE clauses

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This adds the SQL standard feature that adds the SEARCH and CYCLE
clauses to recursive queries to be able to do produce breadth- or
depth-first search orders and detect cycles.  These clauses can be
rewritten into queries using existing syntax, and that is what this
patch does in the rewriter.

Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/db80ceee-6f97-9b4a-8ee8-3ba0c58e5be2@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2021-02-01 13:54:59 +01:00
parent bb513b364b
commit 3696a600e2
28 changed files with 2301 additions and 33 deletions
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54
src/backend/parser/parse_relation.c
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@@ -2235,6 +2235,8 @@ addRangeTableEntryForCTE(ParseState *pstate,
int numaliases;
int varattno;
ListCell *lc;
int n_dontexpand_columns = 0;
ParseNamespaceItem *psi;
Assert(pstate != NULL);
@@ -2267,9 +2269,9 @@ addRangeTableEntryForCTE(ParseState *pstate,
parser_errposition(pstate, rv->location)));
}
rte->coltypes = cte->ctecoltypes;
rte->coltypmods = cte->ctecoltypmods;
rte->colcollations = cte->ctecolcollations;
rte->coltypes = list_copy(cte->ctecoltypes);
rte->coltypmods = list_copy(cte->ctecoltypmods);
rte->colcollations = list_copy(cte->ctecolcollations);
rte->alias = alias;
if (alias)
@@ -2294,6 +2296,34 @@ addRangeTableEntryForCTE(ParseState *pstate,
rte->eref = eref;
if (cte->search_clause)
{
rte->eref->colnames = lappend(rte->eref->colnames, makeString(cte->search_clause->search_seq_column));
if (cte->search_clause->search_breadth_first)
rte->coltypes = lappend_oid(rte->coltypes, RECORDOID);
else
rte->coltypes = lappend_oid(rte->coltypes, RECORDARRAYOID);
rte->coltypmods = lappend_int(rte->coltypmods, -1);
rte->colcollations = lappend_oid(rte->colcollations, InvalidOid);
n_dontexpand_columns += 1;
}
if (cte->cycle_clause)
{
rte->eref->colnames = lappend(rte->eref->colnames, makeString(cte->cycle_clause->cycle_mark_column));
rte->coltypes = lappend_oid(rte->coltypes, cte->cycle_clause->cycle_mark_type);
rte->coltypmods = lappend_int(rte->coltypmods, cte->cycle_clause->cycle_mark_typmod);
rte->colcollations = lappend_oid(rte->colcollations, cte->cycle_clause->cycle_mark_collation);
rte->eref->colnames = lappend(rte->eref->colnames, makeString(cte->cycle_clause->cycle_path_column));
rte->coltypes = lappend_oid(rte->coltypes, RECORDARRAYOID);
rte->coltypmods = lappend_int(rte->coltypmods, -1);
rte->colcollations = lappend_oid(rte->colcollations, InvalidOid);
n_dontexpand_columns += 2;
}
/*
* Set flags and access permissions.
*
@@ -2321,9 +2351,19 @@ addRangeTableEntryForCTE(ParseState *pstate,
* Build a ParseNamespaceItem, but don't add it to the pstate's namespace
* list --- caller must do that if appropriate.
*/
return buildNSItemFromLists(rte, list_length(pstate->p_rtable),
psi = buildNSItemFromLists(rte, list_length(pstate->p_rtable),
rte->coltypes, rte->coltypmods,
rte->colcollations);
/*
* The columns added by search and cycle clauses are not included in star
* expansion in queries contained in the CTE.
*/
if (rte->ctelevelsup > 0)
for (int i = 0; i < n_dontexpand_columns; i++)
psi->p_nscolumns[list_length(psi->p_rte->eref->colnames) - 1 - i].p_dontexpand = true;
return psi;
}
/*
@@ -3008,7 +3048,11 @@ expandNSItemVars(ParseNamespaceItem *nsitem,
const char *colname = strVal(colnameval);
ParseNamespaceColumn *nscol = nsitem->p_nscolumns + colindex;
if (colname[0])
if (nscol->p_dontexpand)
{
/* skip */
}
else if (colname[0])
{
Var *var;