#include "postgres.h"
#include "access/detoast.h"
-#include "access/genam.h"
-#include "access/heaptoast.h"
#include "access/table.h"
+#include "access/tableam.h"
#include "access/toast_internals.h"
#include "common/pg_lzcompress.h"
#include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
#include "utils/rel.h"
static struct varlena *toast_fetch_datum(struct varlena *attr);
static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
int32 sliceoffset,
int32 slicelength);
-static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
- int32 attrsize, int32 sliceoffset,
- int32 slicelength, struct varlena *result);
static struct varlena *toast_decompress_datum(struct varlena *attr);
static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
/* Fetch all chunks */
- heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
- attrsize, result);
+ table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+ attrsize, 0, attrsize, result);
/* Close toast table */
table_close(toastrel, AccessShareLock);
toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
/* Fetch all chunks */
- heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
- sliceoffset, slicelength, result);
+ table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+ attrsize, sliceoffset, slicelength,
+ result);
/* Close toast table */
table_close(toastrel, AccessShareLock);
return result;
}
-/*
- * Fetch a TOAST slice from a heap table.
- *
- * toastrel is the relation from which chunks are to be fetched.
- * valueid identifies the TOAST value from which chunks are being fetched.
- * attrsize is the total size of the TOAST value.
- * sliceoffset is the byte offset within the TOAST value from which to fetch.
- * slicelength is the number of bytes to be fetched from the TOAST value.
- * result is the varlena into which the results should be written.
- */
-static void
-heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
- int32 sliceoffset, int32 slicelength,
- struct varlena *result)
-{
- Relation *toastidxs;
- ScanKeyData toastkey[3];
- TupleDesc toasttupDesc = toastrel->rd_att;
- int nscankeys;
- SysScanDesc toastscan;
- HeapTuple ttup;
- int32 expectedchunk;
- int32 totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
- int startchunk;
- int endchunk;
- int num_indexes;
- int validIndex;
- SnapshotData SnapshotToast;
-
- /* Look for the valid index of toast relation */
- validIndex = toast_open_indexes(toastrel,
- AccessShareLock,
- &toastidxs,
- &num_indexes);
-
- startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
- endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
- Assert(endchunk <= totalchunks);
-
- /*
- * Setup a scan key to fetch from the index. This is either two keys or
- * three depending on the number of chunks.
- */
- ScanKeyInit(&toastkey[0],
- (AttrNumber) 1,
- BTEqualStrategyNumber, F_OIDEQ,
- ObjectIdGetDatum(valueid));
-
- /*
- * No additional condition if fetching all chunks. Otherwise, use an
- * equality condition for one chunk, and a range condition otherwise.
- */
- if (startchunk == 0 && endchunk == totalchunks - 1)
- nscankeys = 1;
- else if (startchunk == endchunk)
- {
- ScanKeyInit(&toastkey[1],
- (AttrNumber) 2,
- BTEqualStrategyNumber, F_INT4EQ,
- Int32GetDatum(startchunk));
- nscankeys = 2;
- }
- else
- {
- ScanKeyInit(&toastkey[1],
- (AttrNumber) 2,
- BTGreaterEqualStrategyNumber, F_INT4GE,
- Int32GetDatum(startchunk));
- ScanKeyInit(&toastkey[2],
- (AttrNumber) 2,
- BTLessEqualStrategyNumber, F_INT4LE,
- Int32GetDatum(endchunk));
- nscankeys = 3;
- }
-
- /* Prepare for scan */
- init_toast_snapshot(&SnapshotToast);
- toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
- &SnapshotToast, nscankeys, toastkey);
-
- /*
- * Read the chunks by index
- *
- * The index is on (valueid, chunkidx) so they will come in order
- */
- expectedchunk = startchunk;
- while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
- {
- int32 curchunk;
- Pointer chunk;
- bool isnull;
- char *chunkdata;
- int32 chunksize;
- int32 expected_size;
- int32 chcpystrt;
- int32 chcpyend;
-
- /*
- * Have a chunk, extract the sequence number and the data
- */
- curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
- Assert(!isnull);
- chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
- Assert(!isnull);
- if (!VARATT_IS_EXTENDED(chunk))
- {
- chunksize = VARSIZE(chunk) - VARHDRSZ;
- chunkdata = VARDATA(chunk);
- }
- else if (VARATT_IS_SHORT(chunk))
- {
- /* could happen due to heap_form_tuple doing its thing */
- chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
- chunkdata = VARDATA_SHORT(chunk);
- }
- else
- {
- /* should never happen */
- elog(ERROR, "found toasted toast chunk for toast value %u in %s",
- valueid, RelationGetRelationName(toastrel));
- chunksize = 0; /* keep compiler quiet */
- chunkdata = NULL;
- }
-
- /*
- * Some checks on the data we've found
- */
- if (curchunk != expectedchunk)
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
- curchunk, expectedchunk, valueid,
- RelationGetRelationName(toastrel))));
- if (curchunk > endchunk)
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
- curchunk,
- startchunk, endchunk, valueid,
- RelationGetRelationName(toastrel))));
- expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
- : attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
- if (chunksize != expected_size)
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
- chunksize, expected_size,
- curchunk, totalchunks, valueid,
- RelationGetRelationName(toastrel))));
-
- /*
- * Copy the data into proper place in our result
- */
- chcpystrt = 0;
- chcpyend = chunksize - 1;
- if (curchunk == startchunk)
- chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
- if (curchunk == endchunk)
- chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
-
- memcpy(VARDATA(result) +
- (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
- chunkdata + chcpystrt,
- (chcpyend - chcpystrt) + 1);
-
- expectedchunk++;
- }
-
- /*
- * Final checks that we successfully fetched the datum
- */
- if (expectedchunk != (endchunk + 1))
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg_internal("missing chunk number %d for toast value %u in %s",
- expectedchunk, valueid,
- RelationGetRelationName(toastrel))));
-
- /* End scan and close indexes. */
- systable_endscan_ordered(toastscan);
- toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-}
-
/* ----------
* toast_decompress_datum -
*
.relation_size = table_block_relation_size,
.relation_needs_toast_table = heapam_relation_needs_toast_table,
.relation_toast_am = heapam_relation_toast_am,
+ .relation_fetch_toast_slice = heap_fetch_toast_slice,
.relation_estimate_size = heapam_estimate_rel_size,
#include "postgres.h"
#include "access/detoast.h"
+#include "access/genam.h"
#include "access/heapam.h"
#include "access/heaptoast.h"
#include "access/toast_helper.h"
#include "access/toast_internals.h"
+#include "utils/fmgroids.h"
/* ----------
return new_tuple;
}
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+ int32 sliceoffset, int32 slicelength,
+ struct varlena *result)
+{
+ Relation *toastidxs;
+ ScanKeyData toastkey[3];
+ TupleDesc toasttupDesc = toastrel->rd_att;
+ int nscankeys;
+ SysScanDesc toastscan;
+ HeapTuple ttup;
+ int32 expectedchunk;
+ int32 totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+ int startchunk;
+ int endchunk;
+ int num_indexes;
+ int validIndex;
+ SnapshotData SnapshotToast;
+
+ /* Look for the valid index of toast relation */
+ validIndex = toast_open_indexes(toastrel,
+ AccessShareLock,
+ &toastidxs,
+ &num_indexes);
+
+ startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+ endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+ Assert(endchunk <= totalchunks);
+
+ /* Set up a scan key to fetch from the index. */
+ ScanKeyInit(&toastkey[0],
+ (AttrNumber) 1,
+ BTEqualStrategyNumber, F_OIDEQ,
+ ObjectIdGetDatum(valueid));
+
+ /*
+ * No additional condition if fetching all chunks. Otherwise, use an
+ * equality condition for one chunk, and a range condition otherwise.
+ */
+ if (startchunk == 0 && endchunk == totalchunks - 1)
+ nscankeys = 1;
+ else if (startchunk == endchunk)
+ {
+ ScanKeyInit(&toastkey[1],
+ (AttrNumber) 2,
+ BTEqualStrategyNumber, F_INT4EQ,
+ Int32GetDatum(startchunk));
+ nscankeys = 2;
+ }
+ else
+ {
+ ScanKeyInit(&toastkey[1],
+ (AttrNumber) 2,
+ BTGreaterEqualStrategyNumber, F_INT4GE,
+ Int32GetDatum(startchunk));
+ ScanKeyInit(&toastkey[2],
+ (AttrNumber) 2,
+ BTLessEqualStrategyNumber, F_INT4LE,
+ Int32GetDatum(endchunk));
+ nscankeys = 3;
+ }
+
+ /* Prepare for scan */
+ init_toast_snapshot(&SnapshotToast);
+ toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+ &SnapshotToast, nscankeys, toastkey);
+
+ /*
+ * Read the chunks by index
+ *
+ * The index is on (valueid, chunkidx) so they will come in order
+ */
+ expectedchunk = startchunk;
+ while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+ {
+ int32 curchunk;
+ Pointer chunk;
+ bool isnull;
+ char *chunkdata;
+ int32 chunksize;
+ int32 expected_size;
+ int32 chcpystrt;
+ int32 chcpyend;
+
+ /*
+ * Have a chunk, extract the sequence number and the data
+ */
+ curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+ Assert(!isnull);
+ chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+ Assert(!isnull);
+ if (!VARATT_IS_EXTENDED(chunk))
+ {
+ chunksize = VARSIZE(chunk) - VARHDRSZ;
+ chunkdata = VARDATA(chunk);
+ }
+ else if (VARATT_IS_SHORT(chunk))
+ {
+ /* could happen due to heap_form_tuple doing its thing */
+ chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+ chunkdata = VARDATA_SHORT(chunk);
+ }
+ else
+ {
+ /* should never happen */
+ elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+ valueid, RelationGetRelationName(toastrel));
+ chunksize = 0; /* keep compiler quiet */
+ chunkdata = NULL;
+ }
+
+ /*
+ * Some checks on the data we've found
+ */
+ if (curchunk != expectedchunk)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+ curchunk, expectedchunk, valueid,
+ RelationGetRelationName(toastrel))));
+ if (curchunk > endchunk)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+ curchunk,
+ startchunk, endchunk, valueid,
+ RelationGetRelationName(toastrel))));
+ expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+ : attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
+ if (chunksize != expected_size)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+ chunksize, expected_size,
+ curchunk, totalchunks, valueid,
+ RelationGetRelationName(toastrel))));
+
+ /*
+ * Copy the data into proper place in our result
+ */
+ chcpystrt = 0;
+ chcpyend = chunksize - 1;
+ if (curchunk == startchunk)
+ chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+ if (curchunk == endchunk)
+ chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
+
+ memcpy(VARDATA(result) +
+ (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+ chunkdata + chcpystrt,
+ (chcpyend - chcpystrt) + 1);
+
+ expectedchunk++;
+ }
+
+ /*
+ * Final checks that we successfully fetched the datum
+ */
+ if (expectedchunk != (endchunk + 1))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg_internal("missing chunk number %d for toast value %u in %s",
+ expectedchunk, valueid,
+ RelationGetRelationName(toastrel))));
+
+ /* End scan and close indexes. */
+ systable_endscan_ordered(toastscan);
+ toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+}
Datum *values,
bool *isnull);
+/* ----------
+ * heap_fetch_toast_slice
+ *
+ * Fetch a slice from a toast value stored in a heap table.
+ * ----------
+ */
+extern void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+ int32 attrsize, int32 sliceoffset,
+ int32 slicelength, struct varlena *result);
+
#endif /* HEAPTOAST_H */
*/
Oid (*relation_toast_am) (Relation rel);
+ /*
+ * This callback is invoked when detoasting a value stored in a toast
+ * table implemented by this AM. See table_relation_fetch_toast_slice()
+ * for more details.
+ */
+ void (*relation_fetch_toast_slice) (Relation toastrel, Oid valueid,
+ int32 attrsize,
+ int32 sliceoffset,
+ int32 slicelength,
+ struct varlena *result);
+
/* ------------------------------------------------------------------------
* Planner related functions.
return rel->rd_tableam->relation_toast_am(rel);
}
+/*
+ * Fetch all or part of a TOAST value from a TOAST table.
+ *
+ * If this AM is never used to implement a TOAST table, then this callback
+ * is not needed. But, if toasted values are ever stored in a table of this
+ * type, then you will need this callback.
+ *
+ * toastrel is the relation in which the toasted value is stored.
+ *
+ * valueid identifes which toast value is to be fetched. For the heap,
+ * this corresponds to the values stored in the chunk_id column.
+ *
+ * attrsize is the total size of the toast value to be fetched.
+ *
+ * sliceoffset is the offset within the toast value of the first byte that
+ * should be fetched.
+ *
+ * slicelength is the number of bytes from the toast value that should be
+ * fetched.
+ *
+ * result is caller-allocated space into which the fetched bytes should be
+ * stored.
+ */
+static inline void
+table_relation_fetch_toast_slice(Relation toastrel, Oid valueid,
+ int32 attrsize, int32 sliceoffset,
+ int32 slicelength, struct varlena *result)
+{
+ return toastrel->rd_tableam->relation_fetch_toast_slice(toastrel, valueid,
+ attrsize,
+ sliceoffset,
+ slicelength,
+ result);
+}
+
/* ----------------------------------------------------------------------------
* Planner related functionality
projects / users / gsingh / postgres.git / commitdiff