Fix pg_mcv_list_items() to produce text[]
The function pg_mcv_list_items() returns values stored in MCV items. The items may contain columns with different data types, so the function was generating text array-like representation, but in an ad-hoc way without properly escaping various characters etc. Fixed by simply building a text[] array, which also makes it easier to use from queries etc. Requires changes to pg_proc entry, so bump catversion. Backpatch to 12, where multi-column MCV lists were introduced. Author: Tomas Vondra Reviewed-by: Dean Rasheed Discussion: https://postgr.es/m/20190618205920.qtlzcu73whfpfqne@development
This commit is contained in:
Tomas Vondra
parent
e365a581c2
commit
4d66285adc
@ -1248,9 +1248,6 @@ Datum
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pg_stats_ext_mcvlist_items(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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int call_cntr;
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int max_calls;
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AttInMetadata *attinmeta;
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/* stuff done only on the first call of the function */
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if (SRF_IS_FIRSTCALL())
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@ -1280,13 +1277,13 @@ pg_stats_ext_mcvlist_items(PG_FUNCTION_ARGS)
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("function returning record called in context "
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"that cannot accept type record")));
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tupdesc = BlessTupleDesc(tupdesc);
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/*
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* generate attribute metadata needed later to produce tuples from raw
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* C strings
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*/
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attinmeta = TupleDescGetAttInMetadata(tupdesc);
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funcctx->attinmeta = attinmeta;
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funcctx->attinmeta = TupleDescGetAttInMetadata(tupdesc);
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MemoryContextSwitchTo(oldcontext);
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}
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@ -1294,111 +1291,78 @@ pg_stats_ext_mcvlist_items(PG_FUNCTION_ARGS)
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/* stuff done on every call of the function */
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funcctx = SRF_PERCALL_SETUP();
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call_cntr = funcctx->call_cntr;
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max_calls = funcctx->max_calls;
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attinmeta = funcctx->attinmeta;
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if (call_cntr < max_calls) /* do when there is more left to send */
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if (funcctx->call_cntr < funcctx->max_calls) /* do when there is more left to send */
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{
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char **values;
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Datum values[5];
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bool nulls[5];
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HeapTuple tuple;
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Datum result;
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StringInfoData itemValues;
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StringInfoData itemNulls;
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ArrayBuildState *astate_values = NULL;
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ArrayBuildState *astate_nulls = NULL;
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int i;
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Oid *outfuncs;
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FmgrInfo *fmgrinfo;
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MCVList *mcvlist;
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MCVItem *item;
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mcvlist = (MCVList *) funcctx->user_fctx;
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Assert(call_cntr < mcvlist->nitems);
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Assert(funcctx->call_cntr < mcvlist->nitems);
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item = &mcvlist->items[call_cntr];
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/*
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* Prepare a values array for building the returned tuple. This should
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* be an array of C strings which will be processed later by the type
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* input functions.
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*/
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values = (char **) palloc0(5 * sizeof(char *));
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values[0] = (char *) palloc(64 * sizeof(char)); /* item index */
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values[3] = (char *) palloc(64 * sizeof(char)); /* frequency */
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values[4] = (char *) palloc(64 * sizeof(char)); /* base frequency */
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outfuncs = (Oid *) palloc0(sizeof(Oid) * mcvlist->ndimensions);
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fmgrinfo = (FmgrInfo *) palloc0(sizeof(FmgrInfo) * mcvlist->ndimensions);
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item = &mcvlist->items[funcctx->call_cntr];
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for (i = 0; i < mcvlist->ndimensions; i++)
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{
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bool isvarlena;
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getTypeOutputInfo(mcvlist->types[i], &outfuncs[i], &isvarlena);
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astate_nulls = accumArrayResult(astate_nulls,
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BoolGetDatum(item->isnull[i]),
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false,
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BOOLOID,
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CurrentMemoryContext);
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fmgr_info(outfuncs[i], &fmgrinfo[i]);
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}
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/* build the arrays of values / nulls */
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initStringInfo(&itemValues);
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initStringInfo(&itemNulls);
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appendStringInfoChar(&itemValues, '{');
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appendStringInfoChar(&itemNulls, '{');
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for (i = 0; i < mcvlist->ndimensions; i++)
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{
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Datum val,
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valout;
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if (i > 0)
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if (!item->isnull[i])
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{
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appendStringInfoString(&itemValues, ", ");
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appendStringInfoString(&itemNulls, ", ");
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}
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bool isvarlena;
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Oid outfunc;
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FmgrInfo fmgrinfo;
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Datum val;
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text *txt;
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if (item->isnull[i])
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valout = CStringGetDatum("NULL");
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/* lookup output func for the type */
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getTypeOutputInfo(mcvlist->types[i], &outfunc, &isvarlena);
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fmgr_info(outfunc, &fmgrinfo);
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val = FunctionCall1(&fmgrinfo, item->values[i]);
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txt = cstring_to_text(DatumGetPointer(val));
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astate_values = accumArrayResult(astate_values,
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PointerGetDatum(txt),
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false,
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TEXTOID,
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CurrentMemoryContext);
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}
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else
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{
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val = item->values[i];
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valout = FunctionCall1(&fmgrinfo[i], val);
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}
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appendStringInfoString(&itemValues, DatumGetCString(valout));
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appendStringInfoString(&itemNulls, item->isnull[i] ? "t" : "f");
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astate_values = accumArrayResult(astate_values,
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(Datum) 0,
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true,
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TEXTOID,
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CurrentMemoryContext);
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}
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appendStringInfoChar(&itemValues, '}');
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appendStringInfoChar(&itemNulls, '}');
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values[0] = Int32GetDatum(funcctx->call_cntr);
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values[1] = PointerGetDatum(makeArrayResult(astate_values, CurrentMemoryContext));
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values[2] = PointerGetDatum(makeArrayResult(astate_nulls, CurrentMemoryContext));
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values[3] = Float8GetDatum(item->frequency);
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values[4] = Float8GetDatum(item->base_frequency);
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snprintf(values[0], 64, "%d", call_cntr);
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snprintf(values[3], 64, "%f", item->frequency);
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snprintf(values[4], 64, "%f", item->base_frequency);
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values[1] = itemValues.data;
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values[2] = itemNulls.data;
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/* no NULLs in the tuple */
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memset(nulls, 0, sizeof(nulls));
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/* build a tuple */
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tuple = BuildTupleFromCStrings(attinmeta, values);
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tuple = heap_form_tuple(funcctx->attinmeta->tupdesc, values, nulls);
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/* make the tuple into a datum */
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result = HeapTupleGetDatum(tuple);
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/* clean up (this is not really necessary) */
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pfree(itemValues.data);
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pfree(itemNulls.data);
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pfree(values[0]);
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pfree(values[3]);
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pfree(values[4]);
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pfree(values);
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SRF_RETURN_NEXT(funcctx, result);
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}
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else /* do when there is no more left */
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@ -53,6 +53,6 @@
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*/
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/* yyyymmddN */
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#define CATALOG_VERSION_NO 201907041
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#define CATALOG_VERSION_NO 201907051
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#endif
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@ -5019,7 +5019,7 @@
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{ oid => '3427', descr => 'details about MCV list items',
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proname => 'pg_mcv_list_items', prorows => '1000', proretset => 't',
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provolatile => 's', prorettype => 'record', proargtypes => 'pg_mcv_list',
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proallargtypes => '{pg_mcv_list,int4,text,_bool,float8,float8}',
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proallargtypes => '{pg_mcv_list,int4,_text,_bool,float8,float8}',
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proargmodes => '{i,o,o,o,o,o}',
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proargnames => '{mcv_list,index,values,nulls,frequency,base_frequency}',
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prosrc => 'pg_stats_ext_mcvlist_items' },
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@ -614,9 +614,9 @@ SELECT m.*
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pg_mcv_list_items(d.stxdmcv) m
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WHERE s.stxname = 'mcv_lists_stats'
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AND d.stxoid = s.oid;
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index | values | nulls | frequency | base_frequency
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-------+-----------+---------+-----------+----------------
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0 | {1, 2, 3} | {f,f,f} | 1 | 1
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index | values | nulls | frequency | base_frequency
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-------+---------+---------+-----------+----------------
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0 | {1,2,3} | {f,f,f} | 1 | 1
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(1 row)
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-- mcv with arrays
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