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compression.c
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compression.c
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/*
* This file and its contents are licensed under the Timescale License.
* Please see the included NOTICE for copyright information and
* LICENSE-TIMESCALE for a copy of the license.
*/
#include "compression/compression.h"
#include <access/heapam.h>
#include <access/htup_details.h>
#include <access/multixact.h>
#include <access/xact.h>
#include <catalog/namespace.h>
#include <catalog/pg_attribute.h>
#include <catalog/pg_type.h>
#include <catalog/index.h>
#include <catalog/heap.h>
#include <common/base64.h>
#include <executor/tuptable.h>
#include <funcapi.h>
#include <libpq/pqformat.h>
#include <miscadmin.h>
#include <nodes/pg_list.h>
#include <storage/lmgr.h>
#include <storage/predicate.h>
#include <utils/builtins.h>
#include <utils/datum.h>
#include <utils/lsyscache.h>
#include <utils/memutils.h>
#include <utils/rel.h>
#include <utils/snapmgr.h>
#include <utils/syscache.h>
#include <utils/tuplesort.h>
#include <utils/typcache.h>
#include <catalog/pg_am.h>
#include <utils.h>
#include "compat/compat.h"
#include "array.h"
#include "chunk.h"
#include "debug_point.h"
#include "deltadelta.h"
#include "dictionary.h"
#include "gorilla.h"
#include "ts_catalog/compression_chunk_size.h"
#include "create.h"
#include "custom_type_cache.h"
#include "segment_meta.h"
#include "ts_catalog/hypertable_compression.h"
#include "ts_catalog/catalog.h"
#include "guc.h"
#include <nodes/print.h>
#define MAX_ROWS_PER_COMPRESSION 1000
/* gap in sequence id between rows, potential for adding rows in gap later */
#define SEQUENCE_NUM_GAP 10
#define COMPRESSIONCOL_IS_SEGMENT_BY(col) ((col)->segmentby_column_index > 0)
#define COMPRESSIONCOL_IS_ORDER_BY(col) ((col)->orderby_column_index > 0)
static const CompressionAlgorithmDefinition definitions[_END_COMPRESSION_ALGORITHMS] = {
[COMPRESSION_ALGORITHM_ARRAY] = ARRAY_ALGORITHM_DEFINITION,
[COMPRESSION_ALGORITHM_DICTIONARY] = DICTIONARY_ALGORITHM_DEFINITION,
[COMPRESSION_ALGORITHM_GORILLA] = GORILLA_ALGORITHM_DEFINITION,
[COMPRESSION_ALGORITHM_DELTADELTA] = DELTA_DELTA_ALGORITHM_DEFINITION,
};
static Compressor *
compressor_for_algorithm_and_type(CompressionAlgorithms algorithm, Oid type)
{
if (algorithm >= _END_COMPRESSION_ALGORITHMS)
elog(ERROR, "invalid compression algorithm %d", algorithm);
return definitions[algorithm].compressor_for_type(type);
}
DecompressionIterator *(*tsl_get_decompression_iterator_init(CompressionAlgorithms algorithm,
bool reverse))(Datum, Oid)
{
if (algorithm >= _END_COMPRESSION_ALGORITHMS)
elog(ERROR, "invalid compression algorithm %d", algorithm);
if (reverse)
return definitions[algorithm].iterator_init_reverse;
else
return definitions[algorithm].iterator_init_forward;
}
typedef struct SegmentInfo
{
Datum val;
FmgrInfo eq_fn;
FunctionCallInfo eq_fcinfo;
int16 typlen;
bool is_null;
bool typ_by_val;
Oid collation;
} SegmentInfo;
typedef struct PerColumn
{
/* the compressor to use for regular columns, NULL for segmenters */
Compressor *compressor;
/*
* Information on the metadata we'll store for this column (currently only min/max).
* Only used for order-by columns right now, will be {-1, NULL} for others.
*/
int16 min_metadata_attr_offset;
int16 max_metadata_attr_offset;
SegmentMetaMinMaxBuilder *min_max_metadata_builder;
/* segment info; only used if compressor is NULL */
SegmentInfo *segment_info;
int16 segmentby_column_index;
} PerColumn;
typedef struct RowCompressor
{
/* memory context reset per-row is stored */
MemoryContext per_row_ctx;
/* the table we're writing the compressed data to */
Relation compressed_table;
BulkInsertState bistate;
/* segment by index Oid if any */
Oid index_oid;
/* in theory we could have more input columns than outputted ones, so we
store the number of inputs/compressors seperately*/
int n_input_columns;
/* info about each column */
struct PerColumn *per_column;
/* the order of columns in the compressed data need not match the order in the
* uncompressed. This array maps each attribute offset in the uncompressed
* data to the corresponding one in the compressed
*/
int16 *uncompressed_col_to_compressed_col;
int16 count_metadata_column_offset;
int16 sequence_num_metadata_column_offset;
/* the number of uncompressed rows compressed into the current compressed row */
uint32 rows_compressed_into_current_value;
/* a unique monotonically increasing (according to order by) id for each compressed row */
int32 sequence_num;
/* cached arrays used to build the HeapTuple */
Datum *compressed_values;
bool *compressed_is_null;
int64 rowcnt_pre_compression;
int64 num_compressed_rows;
} RowCompressor;
static int16 *compress_chunk_populate_keys(Oid in_table, const ColumnCompressionInfo **columns,
int n_columns, int *n_keys_out,
const ColumnCompressionInfo ***keys_out);
static Tuplesortstate *compress_chunk_sort_relation(Relation in_rel, int n_keys,
const ColumnCompressionInfo **keys);
static void row_compressor_init(RowCompressor *row_compressor, TupleDesc uncompressed_tuple_desc,
Relation compressed_table, int num_compression_infos,
const ColumnCompressionInfo **column_compression_info,
int16 *column_offsets, int16 num_columns_in_compressed_table,
bool need_bistate);
static void row_compressor_append_sorted_rows(RowCompressor *row_compressor,
Tuplesortstate *sorted_rel, TupleDesc sorted_desc);
static void row_compressor_finish(RowCompressor *row_compressor);
static void row_compressor_update_group(RowCompressor *row_compressor, TupleTableSlot *row);
static bool row_compressor_new_row_is_in_new_group(RowCompressor *row_compressor,
TupleTableSlot *row);
static void row_compressor_append_row(RowCompressor *row_compressor, TupleTableSlot *row);
static void row_compressor_flush(RowCompressor *row_compressor, CommandId mycid,
bool changed_groups);
static SegmentInfo *segment_info_new(Form_pg_attribute column_attr);
static void segment_info_update(SegmentInfo *segment_info, Datum val, bool is_null);
static bool segment_info_datum_is_in_group(SegmentInfo *segment_info, Datum datum, bool is_null);
static void run_analyze_on_chunk(Oid chunk_relid);
/********************
** compress_chunk **
********************/
static CompressedDataHeader *
get_compressed_data_header(Datum data)
{
CompressedDataHeader *header = (CompressedDataHeader *) PG_DETOAST_DATUM(data);
if (header->compression_algorithm >= _END_COMPRESSION_ALGORITHMS)
elog(ERROR, "invalid compression algorithm %d", header->compression_algorithm);
return header;
}
static void
capture_pgclass_stats(Oid table_oid, int *out_pages, int *out_visible, float *out_tuples)
{
Relation pg_class = table_open(RelationRelationId, RowExclusiveLock);
HeapTuple tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(table_oid));
Form_pg_class classform;
if (!HeapTupleIsValid(tuple))
elog(ERROR, "could not find tuple for relation %u", table_oid);
classform = (Form_pg_class) GETSTRUCT(tuple);
*out_pages = classform->relpages;
*out_visible = classform->relallvisible;
*out_tuples = classform->reltuples;
heap_freetuple(tuple);
table_close(pg_class, RowExclusiveLock);
}
static void
restore_pgclass_stats(Oid table_oid, int pages, int visible, float tuples)
{
Relation pg_class;
HeapTuple tuple;
Form_pg_class classform;
pg_class = table_open(RelationRelationId, RowExclusiveLock);
tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(table_oid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "could not find tuple for relation %u", table_oid);
classform = (Form_pg_class) GETSTRUCT(tuple);
classform->relpages = pages;
classform->relallvisible = visible;
classform->reltuples = tuples;
CatalogTupleUpdate(pg_class, &tuple->t_self, tuple);
heap_freetuple(tuple);
table_close(pg_class, RowExclusiveLock);
}
/* Merge the relstats when merging chunks while compressing them.
* We need to do this in order to update the relstats of the chunk
* that is merged into since the compressed one will be dropped by
* the merge.
*/
extern void
merge_chunk_relstats(Oid merged_relid, Oid compressed_relid)
{
int comp_pages, merged_pages, comp_visible, merged_visible;
float comp_tuples, merged_tuples;
capture_pgclass_stats(compressed_relid, &comp_pages, &comp_visible, &comp_tuples);
capture_pgclass_stats(merged_relid, &merged_pages, &merged_visible, &merged_tuples);
merged_pages += comp_pages;
merged_visible += comp_visible;
merged_tuples += comp_tuples;
restore_pgclass_stats(merged_relid, merged_pages, merged_visible, merged_tuples);
}
/* Truncate the relation WITHOUT applying triggers. This is the
* main difference with ExecuteTruncate. Triggers aren't applied
* because the data remains, just in compressed form. Also don't
* restart sequences. Use the transactional branch through ExecuteTruncate.
*/
static void
truncate_relation(Oid table_oid)
{
List *fks = heap_truncate_find_FKs(list_make1_oid(table_oid));
/* Take an access exclusive lock now. Note that this may very well
* be a lock upgrade. */
Relation rel = table_open(table_oid, AccessExclusiveLock);
Oid toast_relid;
int pages, visible;
float tuples;
/* Chunks should never have fks into them, but double check */
if (fks != NIL)
elog(ERROR, "found a FK into a chunk while truncating");
CheckTableForSerializableConflictIn(rel);
capture_pgclass_stats(table_oid, &pages, &visible, &tuples);
RelationSetNewRelfilenode(rel, rel->rd_rel->relpersistence);
toast_relid = rel->rd_rel->reltoastrelid;
table_close(rel, NoLock);
if (OidIsValid(toast_relid))
{
rel = table_open(toast_relid, AccessExclusiveLock);
RelationSetNewRelfilenode(rel, rel->rd_rel->relpersistence);
Assert(rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED);
table_close(rel, NoLock);
}
#if PG14_LT
int options = 0;
#else
ReindexParams params = { 0 };
ReindexParams *options = ¶ms;
#endif
reindex_relation(table_oid, REINDEX_REL_PROCESS_TOAST, options);
rel = table_open(table_oid, AccessExclusiveLock);
restore_pgclass_stats(table_oid, pages, visible, tuples);
CommandCounterIncrement();
table_close(rel, NoLock);
}
CompressionStats
compress_chunk(Oid in_table, Oid out_table, const ColumnCompressionInfo **column_compression_info,
int num_compression_infos)
{
int n_keys;
ListCell *lc;
int indexscan_direction = NoMovementScanDirection;
List *in_rel_index_oids;
Relation matched_index_rel = NULL;
TupleTableSlot *slot;
IndexScanDesc index_scan;
bool first_iteration = true;
bool changed_groups, compressed_row_is_full;
MemoryContext old_ctx;
CommandId mycid = GetCurrentCommandId(true);
HeapTuple in_table_tp = NULL, index_tp = NULL;
Form_pg_attribute in_table_attr_tp, index_attr_tp;
const ColumnCompressionInfo **keys;
CompressionStats cstat;
/* We want to prevent other compressors from compressing this table,
* and we want to prevent INSERTs or UPDATEs which could mess up our compression.
* We may as well allow readers to keep reading the uncompressed data while
* we are compressing, so we only take an ExclusiveLock instead of AccessExclusive.
*/
Relation in_rel = table_open(in_table, ExclusiveLock);
/* We are _just_ INSERTing into the out_table so in principle we could take
* a RowExclusive lock, and let other operations read and write this table
* as we work. However, we currently compress each table as a oneshot, so
* we're taking the stricter lock to prevent accidents.
*/
Relation out_rel = relation_open(out_table, ExclusiveLock);
int16 *in_column_offsets = compress_chunk_populate_keys(in_table,
column_compression_info,
num_compression_infos,
&n_keys,
&keys);
TupleDesc in_desc = RelationGetDescr(in_rel);
TupleDesc out_desc = RelationGetDescr(out_rel);
in_rel_index_oids = RelationGetIndexList(in_rel);
int i = 0;
/* Before calling row compressor relation should be segmented and sorted as per
* compress_segmentby and compress_orderby column/s configured in ColumnCompressionInfo.
* Cost of sorting can be mitigated if we find an existing BTREE index defined for
* uncompressed chunk otherwise expensive tuplesort will come into play.
*
* The following code is trying to find an existing index that
* matches the ColumnCompressionInfo so that we can skip sequential scan and
* tuplesort.
*
* Matching Criteria for Each IndexAtt[i] and ColumnCompressionInfo Keys[i]
* ========================================================================
* a) Index attnum must match with ColumnCompressionInfo Key {keys[i]}.
* b) Index attOption(ASC/DESC and NULL_FIRST) can be mapped with ColumnCompressionInfo
* orderby_asc and null_first.
*
* BTREE Indexes Ordering
* =====================
* a) ASC[Null_Last] ==> [1]->[2]->NULL
* b) [Null_First]ASC ==> NULL->[1]->[2]
* c) DSC[Null_Last] ==> [2]->[1]->NULL
* d) [Null_First]DSC ==> NULL->[2]->[1]
*/
if (ts_guc_enable_compression_indexscan)
{
foreach (lc, in_rel_index_oids)
{
Oid index_oid = lfirst_oid(lc);
Relation index_rel = index_open(index_oid, AccessShareLock);
IndexInfo *index_info = BuildIndexInfo(index_rel);
int previous_direction = NoMovementScanDirection;
int current_direction = NoMovementScanDirection;
if (n_keys <= index_info->ii_NumIndexKeyAttrs && index_info->ii_Am == BTREE_AM_OID)
{
for (i = 0; i < n_keys; i++)
{
int16 att_num = get_attnum(in_table, NameStr(keys[i]->attname));
int16 option = index_rel->rd_indoption[i];
bool index_orderby_asc = ((option & INDOPTION_DESC) == 0);
bool index_null_first = ((option & INDOPTION_NULLS_FIRST) != 0);
bool is_orderby_asc =
COMPRESSIONCOL_IS_SEGMENT_BY(keys[i]) ? true : keys[i]->orderby_asc;
bool is_null_first =
COMPRESSIONCOL_IS_SEGMENT_BY(keys[i]) ? false : keys[i]->orderby_nullsfirst;
if (att_num == 0 || index_info->ii_IndexAttrNumbers[i] != att_num)
{
break;
}
in_table_tp = SearchSysCacheAttNum(in_table, att_num);
if (!HeapTupleIsValid(in_table_tp))
elog(ERROR,
"table \"%s\" does not have column \"%s\"",
get_rel_name(in_table),
NameStr(keys[i]->attname));
index_tp = SearchSysCacheAttNum(index_oid, i + 1);
if (!HeapTupleIsValid(index_tp))
elog(ERROR,
"index \"%s\" does not have column \"%s\"",
get_rel_name(index_oid),
NameStr(keys[i]->attname));
in_table_attr_tp = (Form_pg_attribute) GETSTRUCT(in_table_tp);
index_attr_tp = (Form_pg_attribute) GETSTRUCT(index_tp);
if (index_orderby_asc == is_orderby_asc && index_null_first == is_null_first &&
in_table_attr_tp->attcollation == index_attr_tp->attcollation)
{
current_direction = ForwardScanDirection;
}
else if (index_orderby_asc != is_orderby_asc &&
index_null_first != is_null_first &&
in_table_attr_tp->attcollation == index_attr_tp->attcollation)
{
current_direction = BackwardScanDirection;
}
else
{
current_direction = NoMovementScanDirection;
break;
}
ReleaseSysCache(in_table_tp);
in_table_tp = NULL;
ReleaseSysCache(index_tp);
index_tp = NULL;
if (previous_direction == NoMovementScanDirection)
{
previous_direction = current_direction;
}
else if (previous_direction != current_direction)
{
break;
}
}
if (n_keys == i && (previous_direction == current_direction &&
current_direction != NoMovementScanDirection))
{
matched_index_rel = index_rel;
indexscan_direction = current_direction;
break;
}
else
{
if (HeapTupleIsValid(in_table_tp))
{
ReleaseSysCache(in_table_tp);
in_table_tp = NULL;
}
if (HeapTupleIsValid(index_tp))
{
ReleaseSysCache(index_tp);
index_tp = NULL;
}
index_close(index_rel, AccessShareLock);
}
}
else
{
index_close(index_rel, AccessShareLock);
}
}
}
Assert(num_compression_infos <= in_desc->natts);
Assert(num_compression_infos <= out_desc->natts);
RowCompressor row_compressor;
row_compressor_init(&row_compressor,
in_desc,
out_rel,
num_compression_infos,
column_compression_info,
in_column_offsets,
out_desc->natts,
true /*need_bistate*/);
if (matched_index_rel != NULL)
{
#ifdef TS_DEBUG
const char *compression_path =
GetConfigOption("timescaledb.show_compression_path_info", true, false);
if (compression_path != NULL && strcmp(compression_path, "on") == 0)
elog(INFO,
"compress_chunk_indexscan_start matched index \"%s\"",
get_rel_name(matched_index_rel->rd_id));
#endif
index_scan = index_beginscan(in_rel, matched_index_rel, GetTransactionSnapshot(), 0, 0);
slot = table_slot_create(in_rel, NULL);
index_rescan(index_scan, NULL, 0, NULL, 0);
while (index_getnext_slot(index_scan, indexscan_direction, slot))
{
slot_getallattrs(slot);
old_ctx = MemoryContextSwitchTo(row_compressor.per_row_ctx);
/* first time through */
if (first_iteration)
{
row_compressor_update_group(&row_compressor, slot);
first_iteration = false;
}
changed_groups = row_compressor_new_row_is_in_new_group(&row_compressor, slot);
compressed_row_is_full =
row_compressor.rows_compressed_into_current_value >= MAX_ROWS_PER_COMPRESSION;
if (compressed_row_is_full || changed_groups)
{
if (row_compressor.rows_compressed_into_current_value > 0)
row_compressor_flush(&row_compressor, mycid, changed_groups);
if (changed_groups)
row_compressor_update_group(&row_compressor, slot);
}
row_compressor_append_row(&row_compressor, slot);
MemoryContextSwitchTo(old_ctx);
ExecClearTuple(slot);
}
run_analyze_on_chunk(in_rel->rd_id);
if (row_compressor.rows_compressed_into_current_value > 0)
row_compressor_flush(&row_compressor, mycid, true);
ExecDropSingleTupleTableSlot(slot);
index_endscan(index_scan);
index_close(matched_index_rel, AccessShareLock);
}
else
{
#ifdef TS_DEBUG
const char *compression_path =
GetConfigOption("timescaledb.show_compression_path_info", true, false);
if (compression_path != NULL && strcmp(compression_path, "on") == 0)
elog(INFO, "compress_chunk_tuplesort_start");
#endif
Tuplesortstate *sorted_rel = compress_chunk_sort_relation(in_rel, n_keys, keys);
row_compressor_append_sorted_rows(&row_compressor, sorted_rel, in_desc);
tuplesort_end(sorted_rel);
}
row_compressor_finish(&row_compressor);
truncate_relation(in_table);
/* Recreate all indexes on out rel, we already have an exclusive lock on it,
* so the strong locks taken by reindex_relation shouldn't matter. */
#if PG14_LT
int options = 0;
#else
ReindexParams params = { 0 };
ReindexParams *options = ¶ms;
#endif
reindex_relation(out_table, 0, options);
table_close(out_rel, NoLock);
table_close(in_rel, NoLock);
cstat.rowcnt_pre_compression = row_compressor.rowcnt_pre_compression;
cstat.rowcnt_post_compression = row_compressor.num_compressed_rows;
return cstat;
}
static int16 *
compress_chunk_populate_keys(Oid in_table, const ColumnCompressionInfo **columns, int n_columns,
int *n_keys_out, const ColumnCompressionInfo ***keys_out)
{
int16 *column_offsets = palloc(sizeof(*column_offsets) * n_columns);
int i;
int n_segment_keys = 0;
*n_keys_out = 0;
for (i = 0; i < n_columns; i++)
{
if (COMPRESSIONCOL_IS_SEGMENT_BY(columns[i]))
n_segment_keys += 1;
if (COMPRESSIONCOL_IS_SEGMENT_BY(columns[i]) || COMPRESSIONCOL_IS_ORDER_BY(columns[i]))
*n_keys_out += 1;
}
if (*n_keys_out == 0)
elog(ERROR, "compression should be configured with an orderby or segment by");
*keys_out = palloc(sizeof(**keys_out) * *n_keys_out);
for (i = 0; i < n_columns; i++)
{
const ColumnCompressionInfo *column = columns[i];
/* valid values for segmentby_columnn_index and orderby_column_index
are > 0 */
int16 segment_offset = column->segmentby_column_index - 1;
int16 orderby_offset = column->orderby_column_index - 1;
AttrNumber compressed_att;
if (COMPRESSIONCOL_IS_SEGMENT_BY(column))
(*keys_out)[segment_offset] = column;
else if (COMPRESSIONCOL_IS_ORDER_BY(column))
(*keys_out)[n_segment_keys + orderby_offset] = column;
compressed_att = get_attnum(in_table, NameStr(column->attname));
if (!AttributeNumberIsValid(compressed_att))
elog(ERROR, "could not find compressed column for \"%s\"", NameStr(column->attname));
column_offsets[i] = AttrNumberGetAttrOffset(compressed_att);
}
return column_offsets;
}
static void compress_chunk_populate_sort_info_for_column(Oid table,
const ColumnCompressionInfo *column,
AttrNumber *att_nums, Oid *sort_operator,
Oid *collation, bool *nulls_first);
static Tuplesortstate *
compress_chunk_sort_relation(Relation in_rel, int n_keys, const ColumnCompressionInfo **keys)
{
TupleDesc tupDesc = RelationGetDescr(in_rel);
Tuplesortstate *tuplesortstate;
HeapTuple tuple;
TableScanDesc heapScan;
TupleTableSlot *heap_tuple_slot = MakeTupleTableSlot(tupDesc, &TTSOpsHeapTuple);
AttrNumber *sort_keys = palloc(sizeof(*sort_keys) * n_keys);
Oid *sort_operators = palloc(sizeof(*sort_operators) * n_keys);
Oid *sort_collations = palloc(sizeof(*sort_collations) * n_keys);
bool *nulls_first = palloc(sizeof(*nulls_first) * n_keys);
int n;
for (n = 0; n < n_keys; n++)
compress_chunk_populate_sort_info_for_column(RelationGetRelid(in_rel),
keys[n],
&sort_keys[n],
&sort_operators[n],
&sort_collations[n],
&nulls_first[n]);
tuplesortstate = tuplesort_begin_heap(tupDesc,
n_keys,
sort_keys,
sort_operators,
sort_collations,
nulls_first,
maintenance_work_mem,
NULL,
false /*=randomAccess*/);
heapScan = table_beginscan(in_rel, GetLatestSnapshot(), 0, (ScanKey) NULL);
for (tuple = heap_getnext(heapScan, ForwardScanDirection); tuple != NULL;
tuple = heap_getnext(heapScan, ForwardScanDirection))
{
if (HeapTupleIsValid(tuple))
{
/* This may not be the most efficient way to do things.
* Since we use begin_heap() the tuplestore expects tupleslots,
* so ISTM that the options are this or maybe putdatum().
*/
ExecStoreHeapTuple(tuple, heap_tuple_slot, false);
tuplesort_puttupleslot(tuplesortstate, heap_tuple_slot);
}
}
heap_endscan(heapScan);
/* Perform an analyze on the chunk to get up-to-date stats before compressing.
* We do it at this point because we've just read out the entire chunk into
* tuplesort, so its pages are likely to be cached and we can save on I/O.
*/
run_analyze_on_chunk(in_rel->rd_id);
ExecDropSingleTupleTableSlot(heap_tuple_slot);
tuplesort_performsort(tuplesortstate);
return tuplesortstate;
}
static void
compress_chunk_populate_sort_info_for_column(Oid table, const ColumnCompressionInfo *column,
AttrNumber *att_nums, Oid *sort_operator,
Oid *collation, bool *nulls_first)
{
HeapTuple tp;
Form_pg_attribute att_tup;
TypeCacheEntry *tentry;
tp = SearchSysCacheAttName(table, NameStr(column->attname));
if (!HeapTupleIsValid(tp))
elog(ERROR,
"table \"%s\" does not have column \"%s\"",
get_rel_name(table),
NameStr(column->attname));
att_tup = (Form_pg_attribute) GETSTRUCT(tp);
/* Other valdation checks beyond just existence of a valid comparison operator could be useful
*/
*att_nums = att_tup->attnum;
*collation = att_tup->attcollation;
*nulls_first = (!(COMPRESSIONCOL_IS_SEGMENT_BY(column))) && column->orderby_nullsfirst;
tentry = lookup_type_cache(att_tup->atttypid, TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
if (COMPRESSIONCOL_IS_SEGMENT_BY(column) || column->orderby_asc)
*sort_operator = tentry->lt_opr;
else
*sort_operator = tentry->gt_opr;
if (!OidIsValid(*sort_operator))
elog(ERROR,
"no valid sort operator for column \"%s\" of type \"%s\"",
NameStr(column->attname),
format_type_be(att_tup->atttypid));
ReleaseSysCache(tp);
}
static void
run_analyze_on_chunk(Oid chunk_relid)
{
VacuumRelation vr = {
.type = T_VacuumRelation,
.relation = NULL,
.oid = chunk_relid,
.va_cols = NIL,
};
VacuumStmt vs = {
.type = T_VacuumStmt,
.rels = list_make1(&vr),
.is_vacuumcmd = false,
.options = NIL,
};
ExecVacuum(NULL, &vs, true);
}
/* Find segment by index for setting the correct sequence number if
* we are trying to roll up chunks while compressing
*/
static Oid
get_compressed_chunk_index(Relation compressed_chunk, int16 *uncompressed_col_to_compressed_col,
PerColumn *per_column, int n_input_columns)
{
ListCell *lc;
int i;
List *index_oids = RelationGetIndexList(compressed_chunk);
foreach (lc, index_oids)
{
Oid index_oid = lfirst_oid(lc);
bool matches = true;
int num_segmentby_columns = 0;
Relation index_rel = index_open(index_oid, AccessShareLock);
IndexInfo *index_info = BuildIndexInfo(index_rel);
for (i = 0; i < n_input_columns; i++)
{
if (per_column[i].segmentby_column_index < 1)
continue;
/* Last member of the index must be the sequence number column. */
if (per_column[i].segmentby_column_index >= index_rel->rd_att->natts)
{
matches = false;
break;
}
int index_att_offset = AttrNumberGetAttrOffset(per_column[i].segmentby_column_index);
if (index_info->ii_IndexAttrNumbers[index_att_offset] !=
AttrOffsetGetAttrNumber(uncompressed_col_to_compressed_col[i]))
{
matches = false;
break;
}
num_segmentby_columns++;
}
/* Check that we have the correct number of index attributes
* and that the last one is the sequence number
*/
if (num_segmentby_columns != index_rel->rd_att->natts - 1 ||
namestrcmp((Name) &index_rel->rd_att->attrs[num_segmentby_columns].attname,
COMPRESSION_COLUMN_METADATA_SEQUENCE_NUM_NAME) != 0)
matches = false;
index_close(index_rel, AccessShareLock);
if (matches)
return index_oid;
}
return InvalidOid;
}
static int32
index_scan_sequence_number(Relation table_rel, Oid index_oid, ScanKeyData *scankey,
int num_scankeys)
{
int32 result = 0;
bool is_null;
Relation index_rel = index_open(index_oid, AccessShareLock);
IndexScanDesc index_scan =
index_beginscan(table_rel, index_rel, GetTransactionSnapshot(), num_scankeys, 0);
index_scan->xs_want_itup = true;
index_rescan(index_scan, scankey, num_scankeys, NULL, 0);
if (index_getnext_tid(index_scan, BackwardScanDirection))
{
result = index_getattr(index_scan->xs_itup,
index_scan->xs_itupdesc
->natts, /* Last attribute of the index is sequence number. */
index_scan->xs_itupdesc,
&is_null);
if (is_null)
result = 0;
}
index_endscan(index_scan);
index_close(index_rel, AccessShareLock);
return result;
}
static int32
table_scan_sequence_number(Relation table_rel, int16 seq_num_column_num, ScanKeyData *scankey,
int num_scankeys)
{
int32 curr_seq_num = 0, max_seq_num = 0;
bool is_null;
HeapTuple compressed_tuple;
Datum seq_num;
TupleDesc in_desc = RelationGetDescr(table_rel);
TableScanDesc heap_scan =
table_beginscan(table_rel, GetLatestSnapshot(), num_scankeys, scankey);
for (compressed_tuple = heap_getnext(heap_scan, ForwardScanDirection); compressed_tuple != NULL;
compressed_tuple = heap_getnext(heap_scan, ForwardScanDirection))
{
Assert(HeapTupleIsValid(compressed_tuple));
seq_num = heap_getattr(compressed_tuple, seq_num_column_num, in_desc, &is_null);
if (!is_null)
{
curr_seq_num = DatumGetInt32(seq_num);
if (max_seq_num < curr_seq_num)
{
max_seq_num = curr_seq_num;
}
}
}
heap_endscan(heap_scan);
return max_seq_num;
}
/* Scan compressed chunk to get the sequence number for current group.
* This is necessary to do when merging chunks. If the chunk is empty,
* scan will always return 0 and the sequence number will start from
* SEQUENCE_NUM_GAP.
*/
static int32
get_sequence_number_for_current_group(Relation table_rel, Oid index_oid,
int16 *uncompressed_col_to_compressed_col,
PerColumn *per_column, int n_input_columns,
int16 seq_num_column_num)
{
/* No point scanning an empty relation. */
if (table_rel->rd_rel->relpages == 0)
return SEQUENCE_NUM_GAP;
/* If there is a suitable index, use index scan otherwise fallback to heap scan. */
bool is_index_scan = OidIsValid(index_oid);
int i, num_scankeys = 0;
int32 result = 0;
for (i = 0; i < n_input_columns; i++)
{
if (per_column[i].segmentby_column_index < 1)
continue;
num_scankeys++;
}
MemoryContext scan_ctx = AllocSetContextCreate(CurrentMemoryContext,
"get max sequence number scan",
ALLOCSET_DEFAULT_SIZES);
MemoryContext old_ctx;
old_ctx = MemoryContextSwitchTo(scan_ctx);
ScanKeyData *scankey = NULL;
if (num_scankeys > 0)
{
scankey = palloc0(sizeof(ScanKeyData) * num_scankeys);
for (i = 0; i < n_input_columns; i++)
{
if (per_column[i].segmentby_column_index < 1)
continue;
PerColumn col = per_column[i];
int16 attno = is_index_scan ?
col.segmentby_column_index :
AttrOffsetGetAttrNumber(uncompressed_col_to_compressed_col[i]);
if (col.segment_info->is_null)
{
ScanKeyEntryInitialize(&scankey[col.segmentby_column_index - 1],
SK_ISNULL | SK_SEARCHNULL,
attno,
InvalidStrategy, /* no strategy */
InvalidOid, /* no strategy subtype */
InvalidOid, /* no collation */
InvalidOid, /* no reg proc for this */
(Datum) 0); /* constant */
}
else
{
ScanKeyEntryInitializeWithInfo(&scankey[col.segmentby_column_index - 1],
0, /* flags */
attno,
BTEqualStrategyNumber,
InvalidOid, /* No strategy subtype. */
col.segment_info->collation,
&col.segment_info->eq_fn,
col.segment_info->val);
}
}
}
if (is_index_scan)
{
/* Index scan should always use at least one scan key to get the sequence number. */
Assert(num_scankeys > 0);
result = index_scan_sequence_number(table_rel, index_oid, scankey, num_scankeys);
}
else
{
/* Table scan can work without scan keys. */
result = table_scan_sequence_number(table_rel, seq_num_column_num, scankey, num_scankeys);
}
MemoryContextSwitchTo(old_ctx);
MemoryContextDelete(scan_ctx);
return result + SEQUENCE_NUM_GAP;
}
/********************
** row_compressor **
********************/
/* num_compression_infos is the number of columns we will write to in the compressed table */
static void
row_compressor_init(RowCompressor *row_compressor, TupleDesc uncompressed_tuple_desc,
Relation compressed_table, int num_compression_infos,
const ColumnCompressionInfo **column_compression_info, int16 *in_column_offsets,
int16 num_columns_in_compressed_table, bool need_bistate)
{
TupleDesc out_desc = RelationGetDescr(compressed_table);
int col;
Name count_metadata_name = DatumGetName(
DirectFunctionCall1(namein, CStringGetDatum(COMPRESSION_COLUMN_METADATA_COUNT_NAME)));
Name sequence_num_metadata_name = DatumGetName(
DirectFunctionCall1(namein,
CStringGetDatum(COMPRESSION_COLUMN_METADATA_SEQUENCE_NUM_NAME)));
AttrNumber count_metadata_column_num =
get_attnum(compressed_table->rd_id, NameStr(*count_metadata_name));
AttrNumber sequence_num_column_num =
get_attnum(compressed_table->rd_id, NameStr(*sequence_num_metadata_name));
Oid compressed_data_type_oid = ts_custom_type_cache_get(CUSTOM_TYPE_COMPRESSED_DATA)->type_oid;
if (count_metadata_column_num == InvalidAttrNumber)
elog(ERROR,
"missing metadata column '%s' in compressed table",
COMPRESSION_COLUMN_METADATA_COUNT_NAME);
if (sequence_num_column_num == InvalidAttrNumber)
elog(ERROR,
"missing metadata column '%s' in compressed table",
COMPRESSION_COLUMN_METADATA_SEQUENCE_NUM_NAME);
*row_compressor = (RowCompressor){
.per_row_ctx = AllocSetContextCreate(CurrentMemoryContext,
"compress chunk per-row",