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Implement the FILTER clause for aggregate function calls.

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This is SQL-standard with a few extensions, namely support for
subqueries and outer references in clause expressions.

catversion bump due to change in Aggref and WindowFunc.

David Fetter, reviewed by Dean Rasheed.
This commit is contained in:
Noah Misch
2013-07-16 20:15:36 -04:00
parent 7a8e9f298e
commit b560ec1b0d
35 changed files with 403 additions and 51 deletions
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29
src/backend/parser/parse_agg.c
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@ -44,7 +44,7 @@ typedef struct
int sublevels_up;
} check_ungrouped_columns_context;
static int check_agg_arguments(ParseState *pstate, List *args);
static int check_agg_arguments(ParseState *pstate, List *args, Expr *filter);
static bool check_agg_arguments_walker(Node *node,
check_agg_arguments_context *context);
static void check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
@ -160,7 +160,7 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
* Check the arguments to compute the aggregate's level and detect
* improper nesting.
*/
min_varlevel = check_agg_arguments(pstate, agg->args);
min_varlevel = check_agg_arguments(pstate, agg->args, agg->aggfilter);
agg->agglevelsup = min_varlevel;
/* Mark the correct pstate level as having aggregates */
@ -207,6 +207,9 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
case EXPR_KIND_HAVING:
/* okay */
break;
case EXPR_KIND_FILTER:
errkind = true;
break;
case EXPR_KIND_WINDOW_PARTITION:
/* okay */
break;
@ -299,8 +302,8 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
* one is its parent, etc).
*
* The aggregate's level is the same as the level of the lowest-level variable
* or aggregate in its arguments; or if it contains no variables at all, we
* presume it to be local.
* or aggregate in its arguments or filter expression; or if it contains no
* variables at all, we presume it to be local.
*
* We also take this opportunity to detect any aggregates or window functions
* nested within the arguments. We can throw error immediately if we find
@ -309,7 +312,7 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
* which we can't know until we finish scanning the arguments.
*/
static int
check_agg_arguments(ParseState *pstate, List *args)
check_agg_arguments(ParseState *pstate, List *args, Expr *filter)
{
int agglevel;
check_agg_arguments_context context;
@ -323,6 +326,10 @@ check_agg_arguments(ParseState *pstate, List *args)
check_agg_arguments_walker,
(void *) &context);
(void) expression_tree_walker((Node *) filter,
check_agg_arguments_walker,
(void *) &context);
/*
* If we found no vars nor aggs at all, it's a level-zero aggregate;
* otherwise, its level is the minimum of vars or aggs.
@ -481,6 +488,9 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
case EXPR_KIND_HAVING:
errkind = true;
break;
case EXPR_KIND_FILTER:
errkind = true;
break;
case EXPR_KIND_WINDOW_PARTITION:
case EXPR_KIND_WINDOW_ORDER:
case EXPR_KIND_WINDOW_FRAME_RANGE:
@ -807,11 +817,10 @@ check_ungrouped_columns_walker(Node *node,
/*
* If we find an aggregate call of the original level, do not recurse into
* its arguments; ungrouped vars in the arguments are not an error. We can
* also skip looking at the arguments of aggregates of higher levels,
* since they could not possibly contain Vars that are of concern to us
* (see transformAggregateCall). We do need to look into the arguments of
* aggregates of lower levels, however.
* its arguments or filter; ungrouped vars there are not an error. We can
* also skip looking at aggregates of higher levels, since they could not
* possibly contain Vars of concern to us (see transformAggregateCall).
* We do need to look at aggregates of lower levels, however.
*/
if (IsA(node, Aggref) &&
(int) ((Aggref *) node)->agglevelsup >= context->sublevels_up)