From 784e762e886e6f72f548da86a27cd2ead87dbd1c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 21 Nov 2013 19:37:02 -0500 Subject: Support multi-argument UNNEST(), and TABLE() syntax for multiple functions. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch adds the ability to write TABLE( function1(), function2(), ...) as a single FROM-clause entry. The result is the concatenation of the first row from each function, followed by the second row from each function, etc; with NULLs inserted if any function produces fewer rows than others. This is believed to be a much more useful behavior than what Postgres currently does with multiple SRFs in a SELECT list. This syntax also provides a reasonable way to combine use of column definition lists with WITH ORDINALITY: put the column definition list inside TABLE(), where it's clear that it doesn't control the ordinality column as well. Also implement SQL-compliant multiple-argument UNNEST(), by turning UNNEST(a,b,c) into TABLE(unnest(a), unnest(b), unnest(c)). The SQL standard specifies TABLE() with only a single function, not multiple functions, and it seems to require an implicit UNNEST() which is not what this patch does. There may be something wrong with that reading of the spec, though, because if it's right then the spec's TABLE() is just a pointless alternative spelling of UNNEST(). After further review of that, we might choose to adopt a different syntax for what this patch does, but in any case this functionality seems clearly worthwhile. Andrew Gierth, reviewed by Zoltán Böszörményi and Heikki Linnakangas, and significantly revised by me --- src/include/nodes/execnodes.h | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) (limited to 'src/include/nodes/execnodes.h') diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index bedcf040a7a..5a4034729cf 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1395,24 +1395,26 @@ typedef struct SubqueryScanState * function appearing in FROM (typically a function returning set). * * eflags node's capability flags - * ordinal column value for WITH ORDINALITY - * scan_tupdesc scan tuple descriptor - * func_tupdesc function tuple descriptor - * func_slot function result slot, or null - * tuplestorestate private state of tuplestore.c - * funcexpr state for function expression being evaluated + * ordinality is this scan WITH ORDINALITY? + * simple true if we have 1 function and no ordinality + * ordinal current ordinal column value + * nfuncs number of functions being executed + * funcstates per-function execution states (private in + * nodeFunctionscan.c) * ---------------- */ +struct FunctionScanPerFuncState; + typedef struct FunctionScanState { ScanState ss; /* its first field is NodeTag */ int eflags; - int64 ordinal; - TupleDesc scan_tupdesc; - TupleDesc func_tupdesc; - TupleTableSlot *func_slot; - Tuplestorestate *tuplestorestate; - ExprState *funcexpr; + bool ordinality; + bool simple; + int64 ordinal; + int nfuncs; + struct FunctionScanPerFuncState *funcstates; /* array of length + * nfuncs */ } FunctionScanState; /* ---------------- -- cgit v1.2.3