#include "postgres.h"
#include "access/brin_tuple.h"
+#include "access/detoast.h"
+#include "access/heaptoast.h"
#include "access/htup_details.h"
+#include "access/toast_internals.h"
#include "access/tupdesc.h"
#include "access/tupmacs.h"
#include "utils/datum.h"
#include "utils/memutils.h"
+
+/*
+ * This enables de-toasting of index entries. Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
+
+
static inline void brin_deconstruct_tuple(BrinDesc *brdesc,
char *tp, bits8 *nullbits, bool nulls,
Datum *values, bool *allnulls, bool *hasnulls);
Size len,
hoff,
data_len;
+ int i;
+
+#ifdef TOAST_INDEX_HACK
+ Datum *untoasted_values;
+ int nuntoasted = 0;
+#endif
Assert(brdesc->bd_totalstored > 0);
phony_nullbitmap = (bits8 *)
palloc(sizeof(bits8) * BITMAPLEN(brdesc->bd_totalstored));
+#ifdef TOAST_INDEX_HACK
+ untoasted_values = (Datum *) palloc(sizeof(Datum) * brdesc->bd_totalstored);
+#endif
+
/*
* Set up the values/nulls arrays for heap_fill_tuple
*/
if (tuple->bt_columns[keyno].bv_hasnulls)
anynulls = true;
+ /*
+ * Now obtain the values of each stored datum. Note that some values
+ * might be toasted, and we cannot rely on the original heap values
+ * sticking around forever, so we must detoast them. Also try to
+ * compress them.
+ */
for (datumno = 0;
datumno < brdesc->bd_info[keyno]->oi_nstored;
datumno++)
- values[idxattno++] = tuple->bt_columns[keyno].bv_values[datumno];
+ {
+ Datum value = tuple->bt_columns[keyno].bv_values[datumno];
+
+#ifdef TOAST_INDEX_HACK
+
+ /* We must look at the stored type, not at the index descriptor. */
+ TypeCacheEntry *atttype = brdesc->bd_info[keyno]->oi_typcache[datumno];
+
+ /* Do we need to free the value at the end? */
+ bool free_value = false;
+
+ /* For non-varlena types we don't need to do anything special */
+ if (atttype->typlen != -1)
+ {
+ values[idxattno++] = value;
+ continue;
+ }
+
+ /*
+ * Do nothing if value is not of varlena type. We don't need to
+ * care about NULL values here, thanks to bv_allnulls above.
+ *
+ * If value is stored EXTERNAL, must fetch it so we are not
+ * depending on outside storage.
+ *
+ * XXX Is this actually true? Could it be that the summary is
+ * NULL even for range with non-NULL data? E.g. degenerate bloom
+ * filter may be thrown away, etc.
+ */
+ if (VARATT_IS_EXTERNAL(DatumGetPointer(value)))
+ {
+ value = PointerGetDatum(detoast_external_attr((struct varlena *)
+ DatumGetPointer(value)));
+ free_value = true;
+ }
+
+ /*
+ * If value is above size target, and is of a compressible datatype,
+ * try to compress it in-line.
+ */
+ if (!VARATT_IS_EXTENDED(DatumGetPointer(value)) &&
+ VARSIZE(DatumGetPointer(value)) > TOAST_INDEX_TARGET &&
+ (atttype->typstorage == TYPSTORAGE_EXTENDED ||
+ atttype->typstorage == TYPSTORAGE_MAIN))
+ {
+ Datum cvalue = toast_compress_datum(value);
+
+ if (DatumGetPointer(cvalue) != NULL)
+ {
+ /* successful compression */
+ if (free_value)
+ pfree(DatumGetPointer(value));
+
+ value = cvalue;
+ free_value = true;
+ }
+ }
+
+ /*
+ * If we untoasted / compressed the value, we need to free it
+ * after forming the index tuple.
+ */
+ if (free_value)
+ untoasted_values[nuntoasted++] = value;
+
+#endif
+
+ values[idxattno++] = value;
+ }
}
/* Assert we did not overrun temp arrays */
pfree(nulls);
pfree(phony_nullbitmap);
+#ifdef TOAST_INDEX_HACK
+ for (i = 0; i < nuntoasted; i++)
+ pfree(DatumGetPointer(untoasted_values[i]));
+#endif
+
/*
* Now fill in the real null bitmasks. allnulls first.
*/
Filter: (b = 1)
(2 rows)
+-- make sure data are properly de-toasted in BRIN index
+CREATE TABLE brintest_3 (a text, b text, c text, d text);
+-- long random strings (~2000 chars each, so ~6kB for min/max on two
+-- columns) to trigger toasting
+WITH rand_value AS (SELECT string_agg(md5(i::text),'') AS val FROM generate_series(1,60) s(i))
+INSERT INTO brintest_3
+SELECT val, val, val, val FROM rand_value;
+CREATE INDEX brin_test_toast_idx ON brintest_3 USING brin (b, c);
+DELETE FROM brintest_3;
+-- We need to wait a bit for all transactions to complete, so that the
+-- vacuum actually removes the TOAST rows. Creating an index concurrently
+-- is a one way to achieve that, because it does exactly such wait.
+CREATE INDEX CONCURRENTLY brin_test_temp_idx ON brintest_3(a);
+DROP INDEX brin_test_temp_idx;
+-- vacuum the table, to discard TOAST data
+VACUUM brintest_3;
+-- retry insert with a different random-looking (but deterministic) value
+-- the value is different, and so should replace either min or max in the
+-- brin summary
+WITH rand_value AS (SELECT string_agg(md5((-i)::text),'') AS val FROM generate_series(1,60) s(i))
+INSERT INTO brintest_3
+SELECT val, val, val, val FROM rand_value;
+-- now try some queries, accessing the brin index
+SET enable_seqscan = off;
+EXPLAIN (COSTS OFF)
+SELECT * FROM brintest_3 WHERE b < '0';
+ QUERY PLAN
+------------------------------------------------
+ Bitmap Heap Scan on brintest_3
+ Recheck Cond: (b < '0'::text)
+ -> Bitmap Index Scan on brin_test_toast_idx
+ Index Cond: (b < '0'::text)
+(4 rows)
+
+SELECT * FROM brintest_3 WHERE b < '0';
+ a | b | c | d
+---+---+---+---
+(0 rows)
+
+DROP TABLE brintest_3;
+RESET enable_seqscan;
EXPLAIN (COSTS OFF) SELECT * FROM brin_test WHERE a = 1;
-- Ensure brin index is not used when values are not correlated
EXPLAIN (COSTS OFF) SELECT * FROM brin_test WHERE b = 1;
+
+-- make sure data are properly de-toasted in BRIN index
+CREATE TABLE brintest_3 (a text, b text, c text, d text);
+
+-- long random strings (~2000 chars each, so ~6kB for min/max on two
+-- columns) to trigger toasting
+WITH rand_value AS (SELECT string_agg(md5(i::text),'') AS val FROM generate_series(1,60) s(i))
+INSERT INTO brintest_3
+SELECT val, val, val, val FROM rand_value;
+
+CREATE INDEX brin_test_toast_idx ON brintest_3 USING brin (b, c);
+DELETE FROM brintest_3;
+
+-- We need to wait a bit for all transactions to complete, so that the
+-- vacuum actually removes the TOAST rows. Creating an index concurrently
+-- is a one way to achieve that, because it does exactly such wait.
+CREATE INDEX CONCURRENTLY brin_test_temp_idx ON brintest_3(a);
+DROP INDEX brin_test_temp_idx;
+
+-- vacuum the table, to discard TOAST data
+VACUUM brintest_3;
+
+-- retry insert with a different random-looking (but deterministic) value
+-- the value is different, and so should replace either min or max in the
+-- brin summary
+WITH rand_value AS (SELECT string_agg(md5((-i)::text),'') AS val FROM generate_series(1,60) s(i))
+INSERT INTO brintest_3
+SELECT val, val, val, val FROM rand_value;
+
+-- now try some queries, accessing the brin index
+SET enable_seqscan = off;
+
+EXPLAIN (COSTS OFF)
+SELECT * FROM brintest_3 WHERE b < '0';
+
+SELECT * FROM brintest_3 WHERE b < '0';
+
+DROP TABLE brintest_3;
+RESET enable_seqscan;
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