diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index e0b8a4e..c4ac2bd 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -1014,6 +1014,22 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI + + wal_compress_update (boolean) + + + Enables or disables the WAL tuple compression for UPDATE + on this table. Default value of this option is false to maintain + backward compatability for the command. If true, all the update + operations on this table which will place the new tuple on same page + as it's original tuple will compress the WAL for new tuple and + subsequently reduce the WAL volume. It is recommended to enable + this option for tables where UPDATE changes less than + 50 percent of tuple data. + + + + diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c index aea9d40..3bf5728 100644 --- a/src/backend/access/common/heaptuple.c +++ b/src/backend/access/common/heaptuple.c @@ -60,6 +60,7 @@ #include "access/sysattr.h" #include "access/tuptoaster.h" #include "executor/tuptable.h" +#include "utils/pg_rbcompress.h" /* Does att's datatype allow packing into the 1-byte-header varlena format? */ @@ -617,6 +618,44 @@ heap_copytuple_with_tuple(HeapTuple src, HeapTuple dest) memcpy((char *) dest->t_data, (char *) src->t_data, src->t_len); } +/* ---------------- + * heap_delta_encode + * + * Calculate the delta between two tuples and generate + * encoded wal tuple (EWT), using pgrb. The result is stored + * in *encdata. + * ---------------- + */ +bool +heap_delta_encode(TupleDesc tupleDesc, HeapTuple oldtup, HeapTuple newtup, + char *encdata, uint32 *enclen) +{ + return pgrb_delta_encode( + (char *) newtup->t_data + offsetof(HeapTupleHeaderData, t_bits), + newtup->t_len - offsetof(HeapTupleHeaderData, t_bits), + (char *) oldtup->t_data + offsetof(HeapTupleHeaderData, t_bits), + oldtup->t_len - offsetof(HeapTupleHeaderData, t_bits), + encdata, enclen, NULL + ); +} + +/* ---------------- + * heap_delta_decode + * + * Decode a tuple using delta-encoded WAL tuple and old tuple version. + * ---------------- + */ +void +heap_delta_decode(char *encdata, uint32 enclen, HeapTuple oldtup, HeapTuple newtup) +{ + pgrb_delta_decode(encdata, enclen, + (char *) newtup->t_data + offsetof(HeapTupleHeaderData, t_bits), + MaxHeapTupleSize - offsetof(HeapTupleHeaderData, t_bits), + &newtup->t_len, + (char *) oldtup->t_data + offsetof(HeapTupleHeaderData, t_bits), + oldtup->t_len - offsetof(HeapTupleHeaderData, t_bits)); +} + /* * heap_form_tuple * construct a tuple from the given values[] and isnull[] arrays, diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c index fa08c45..2123a61 100644 --- a/src/backend/access/common/reloptions.c +++ b/src/backend/access/common/reloptions.c @@ -85,6 +85,14 @@ static relopt_bool boolRelOpts[] = }, false }, + { + { + "wal_compress_update", + "Compress the wal tuple for update operation on this relation", + RELOPT_KIND_HEAP + }, + true + }, /* list terminator */ {{NULL}} }; @@ -1175,7 +1183,9 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind) {"check_option", RELOPT_TYPE_STRING, offsetof(StdRdOptions, check_option_offset)}, {"user_catalog_table", RELOPT_TYPE_BOOL, - offsetof(StdRdOptions, user_catalog_table)} + offsetof(StdRdOptions, user_catalog_table)}, + {"wal_compress_update", RELOPT_TYPE_BOOL, + offsetof(StdRdOptions, wal_compress_update)} }; options = parseRelOptions(reloptions, validate, kind, &numoptions); diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index a771ccb..2724188 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -70,6 +70,7 @@ #include "utils/snapmgr.h" #include "utils/syscache.h" #include "utils/tqual.h" +#include "utils/pg_rbcompress.h" /* GUC variable */ @@ -6597,6 +6598,12 @@ log_heap_update(Relation reln, Buffer oldbuf, XLogRecPtr recptr; XLogRecData rdata[7]; Page page = BufferGetPage(newbuf); + char *newtupdata; + int newtuplen; + bool compressed = false; + + /* Structure which holds EWT */ + char buf[MaxHeapTupleSize]; bool need_tuple_data = RelationIsLogicallyLogged(reln); /* Caller should not call me on a non-WAL-logged relation */ @@ -6607,6 +6614,37 @@ log_heap_update(Relation reln, Buffer oldbuf, else info = XLOG_HEAP_UPDATE; + newtupdata = ((char *) newtup->t_data) + offsetof(HeapTupleHeaderData, t_bits); + newtuplen = newtup->t_len - offsetof(HeapTupleHeaderData, t_bits); + + /* + * EWT can be generated for all new tuple versions created by Update + * operation. Currently we do it when both the old and new tuple versions + * are on same page, because during recovery if the page containing old + * tuple is corrupt, it should not cascade that corruption to other pages. + * Under the general assumption that for long runs most updates tend to + * create new tuple version on same page, there should not be significant + * impact on WAL reduction or performance. + * + * We should not generate EWT when we need to backup the whole block in + * WAL as in that case there is no saving by reduced WAL size. + */ + + if (RelationIsEnabledForWalCompression(reln) && + (oldbuf == newbuf) && + !XLogCheckBufferNeedsBackup(newbuf)) + { + uint32 enclen; + + /* Delta-encode the new tuple using the old tuple */ + if (heap_delta_encode(reln->rd_att, oldtup, newtup, buf, &enclen)) + { + compressed = true; + newtupdata = buf; + newtuplen = enclen; + } + } + xlrec.target.node = reln->rd_node; xlrec.target.tid = oldtup->t_self; xlrec.old_xmax = HeapTupleHeaderGetRawXmax(oldtup->t_data); @@ -6619,6 +6657,8 @@ log_heap_update(Relation reln, Buffer oldbuf, xlrec.newtid = newtup->t_self; if (new_all_visible_cleared) xlrec.flags |= XLOG_HEAP_NEW_ALL_VISIBLE_CLEARED; + if (compressed) + xlrec.flags |= XLOG_HEAP_DELTA_ENCODED; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapUpdate; @@ -6634,7 +6674,7 @@ log_heap_update(Relation reln, Buffer oldbuf, xlhdr.header.t_infomask2 = newtup->t_data->t_infomask2; xlhdr.header.t_infomask = newtup->t_data->t_infomask; xlhdr.header.t_hoff = newtup->t_data->t_hoff; - xlhdr.t_len = newtup->t_len - offsetof(HeapTupleHeaderData, t_bits); + xlhdr.t_len = newtuplen; /* * As with insert records, we need not store the rdata[2] segment @@ -6647,10 +6687,13 @@ log_heap_update(Relation reln, Buffer oldbuf, rdata[2].buffer_std = true; rdata[2].next = &(rdata[3]); - /* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */ - rdata[3].data = (char *) newtup->t_data - + offsetof(HeapTupleHeaderData, t_bits); - rdata[3].len = newtup->t_len - offsetof(HeapTupleHeaderData, t_bits); + /* + * PG73FORMAT: write bitmap [+ padding] [+ oid] + data OR + * PG94FORMAT [If encoded]: Control byte + history reference (2 - 3)bytes + * + literal byte + ... + */ + rdata[3].data = newtupdata; + rdata[3].len = newtuplen; rdata[3].buffer = need_tuple_data ? InvalidBuffer : newbuf; rdata[3].buffer_std = true; rdata[3].next = NULL; @@ -7739,7 +7782,10 @@ heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool hot_update) Page page; OffsetNumber offnum; ItemId lp = NULL; + HeapTupleData newtup; + HeapTupleData oldtup; HeapTupleHeader htup; + HeapTupleHeader oldtupdata = NULL; struct { HeapTupleHeaderData hdr; @@ -7814,7 +7860,7 @@ heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool hot_update) if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp)) elog(PANIC, "heap_update_redo: invalid lp"); - htup = (HeapTupleHeader) PageGetItem(page, lp); + oldtupdata = htup = (HeapTupleHeader) PageGetItem(page, lp); htup->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED); htup->t_infomask2 &= ~HEAP_KEYS_UPDATED; @@ -7923,10 +7969,31 @@ newsame:; Assert(newlen <= MaxHeapTupleSize); htup = &tbuf.hdr; MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData)); - /* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */ - memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits), - (char *) xlrec + hsize, - newlen); + + /* + * If the record is EWT then decode it. + */ + if (xlrec->flags & XLOG_HEAP_DELTA_ENCODED) + { + /* + * PG94FORMAT: Control byte + history reference (2 - 3)bytes + * + literal byte + ... + */ + oldtup.t_data = oldtupdata; + oldtup.t_len = ItemIdGetLength(lp); + newtup.t_data = htup; + + heap_delta_decode((char *) xlrec + hsize, newlen, &oldtup, &newtup); + newlen = newtup.t_len; + } + else + { + /* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */ + memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits), + (char *) xlrec + hsize, + newlen); + } + newlen += offsetof(HeapTupleHeaderData, t_bits); htup->t_infomask2 = xlhdr.header.t_infomask2; htup->t_infomask = xlhdr.header.t_infomask; diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index b333d82..92c4f00 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2327,6 +2327,28 @@ XLogRecPtrToBytePos(XLogRecPtr ptr) } /* + * Determine whether the buffer referenced has to be backed up. Since we don't + * yet have the insert lock, fullPageWrites and forcePageWrites could change + * later, but will not cause any problem because this function is used only to + * identify whether EWT is required for update. + */ +bool +XLogCheckBufferNeedsBackup(Buffer buffer) +{ + bool doPageWrites; + Page page; + + page = BufferGetPage(buffer); + + doPageWrites = XLogCtl->Insert.fullPageWrites || XLogCtl->Insert.forcePageWrites; + + if (doPageWrites && PageGetLSN(page) <= RedoRecPtr) + return true; /* buffer requires backup */ + + return false; /* buffer does not need to be backed up */ +} + +/* * Determine whether the buffer referenced by an XLogRecData item has to * be backed up, and if so fill a BkpBlock struct for it. In any case * save the buffer's LSN at *lsn. diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile index 1ae9fa0..04dc17c 100644 --- a/src/backend/utils/adt/Makefile +++ b/src/backend/utils/adt/Makefile @@ -26,7 +26,7 @@ OBJS = acl.o arrayfuncs.o array_selfuncs.o array_typanalyze.o \ rowtypes.o regexp.o regproc.o ruleutils.o selfuncs.o \ tid.o timestamp.o varbit.o varchar.o varlena.o version.o xid.o \ network.o mac.o inet_cidr_ntop.o inet_net_pton.o \ - ri_triggers.o pg_lzcompress.o pg_locale.o formatting.o \ + ri_triggers.o pg_lzcompress.o pg_rbcompress.o pg_locale.o formatting.o \ ascii.o quote.o pgstatfuncs.o encode.o dbsize.o genfile.o trigfuncs.o \ tsginidx.o tsgistidx.o tsquery.o tsquery_cleanup.o tsquery_gist.o \ tsquery_op.o tsquery_rewrite.o tsquery_util.o tsrank.o \ diff --git a/src/backend/utils/adt/pg_rbcompress.c b/src/backend/utils/adt/pg_rbcompress.c new file mode 100644 index 0000000..fcbb74c --- /dev/null +++ b/src/backend/utils/adt/pg_rbcompress.c @@ -0,0 +1,634 @@ +/* ---------- + * pg_rbcompress.c - + * + * This is a delta encoding scheme specific to PostgreSQL and designed + * to compress similar tuples. It can be used as it is or extended for + * other purpose in PostgrSQL if required. + * + * It uses a simple history table to represent history data (old tuple) + * and then compress source string (new tuple) using the history data. + * It uses LZ compression format to store encoded string except for + * using PGLZ_Header. + * + * + * The decompression algorithm works exactly same as LZ, except + * for processing of its PGLZ_Header. + * + * Copyright (c) 1999-2014, PostgreSQL Global Development Group + * + * src/backend/utils/adt/pg_rbcompress.c + * ---------- + */ +#include "postgres.h" + +#include + +#include "utils/pg_rbcompress.h" + + +/* ---------- + * Local definitions + * ---------- + */ +#define PGRB_MAX_HISTORY_LISTS 8192 /* must be power of 2 */ +#define PGRB_HISTORY_SIZE 4096 +#define PGRB_MAX_MATCH 273 +#define PGRB_CHUNK_SIZE 4 + + + +/* ---------- + * The provided standard strategies + * ---------- + */ +static const PGRB_Strategy strategy_default_data = { + 32, /* Data chunks less than 32 bytes are not + * compressed */ + INT_MAX, /* No upper limit on what we'll try to + * compress */ + 25, /* Require 25% compression rate, or not worth + * it */ + 1024, /* Give up if no compression in the first 1KB */ + 128, /* Stop history lookup if a match of 128 bytes + * is found */ + 10 /* Lower good match size by 10% at every loop + * iteration */ +}; +const PGRB_Strategy *const PGRB_strategy_default = &strategy_default_data; + + +typedef struct PGRB_HistEntry +{ + struct PGRB_HistEntry *next; /* links for my hash key's list */ + const char *ck_start_pos; /* chunk start position */ +} PGRB_HistEntry; + +/* ---------- + * Statically allocated work arrays for history + * ---------- + */ +static int16 hist_start[PGRB_MAX_HISTORY_LISTS]; +static PGRB_HistEntry rb_hist_entries[PGRB_HISTORY_SIZE + 1]; + +/* + * Element 0 in hist_entries is unused, and means 'invalid'. Likewise, + * INVALID_ENTRY_PTR in next/prev pointers mean 'invalid'. + */ +#define INVALID_ENTRY 0 +#define RB_INVALID_ENTRY_PTR (&rb_hist_entries[INVALID_ENTRY]) + + +/* ---------- + * pgrb_hist_idx - + * + * Computes the history table slot for the lookup by the next 4 + * characters in the input. + * + * NB: because we use the next 4 characters, we are not guaranteed to + * find 3-character matches; they very possibly will be in the wrong + * hash list. This seems an acceptable tradeoff for spreading out the + * hash keys more. + * ---------- + */ +#define pgrb_hist_idx(_s, _mask) ( \ + (((_s)[0] << 6) ^ ((_s)[1] << 4) ^ \ + ((_s)[2] << 2) ^ (_s)[3]) & (_mask) \ + ) + +/* The same, calculated in a rolling fashion */ +#define pgrb_hash_init(_p,hindex) \ + hindex = ((_p)[0] << 4) ^ ((_p)[1] << 2) ^ ((_p)[2]) + +#define pgrb_hash_roll(_p, hindex) \ + hindex = (hindex << 2) ^ (_p)[3] + +#define pgrb_hash_unroll(_p, hindex) \ + hindex = hindex ^ ((_p)[0] << 6) + +/* + * An version of pglz_hist_add() that doesn't do recycling. Can be used if + * you know the input fits in PGRB_HISTORY_SIZE. + */ +#define pgrb_hist_add_no_recycle(_hs,_he,_hn,_s, _hindex) \ +do { \ + int16 *__myhsp = &(_hs)[_hindex]; \ + PGRB_HistEntry *__myhe = &(_he)[_hn]; \ + __myhe->next = &(_he)[*__myhsp]; \ + __myhe->ck_start_pos = (_s); \ + *__myhsp = _hn; \ + ++(_hn); \ +} while (0) + + +/* ---------- + * pgrb_out_ctrl - + * + * Outputs the last and allocates a new control byte if needed. + * ---------- + */ +#define pgrb_out_ctrl(__ctrlp,__ctrlb,__ctrl,__buf) \ +do { \ + if ((__ctrl & 0xff) == 0) \ + { \ + *(__ctrlp) = __ctrlb; \ + __ctrlp = (__buf)++; \ + __ctrlb = 0; \ + __ctrl = 1; \ + } \ +} while (0) + + +/* ---------- + * pgrb_out_literal - + * + * Outputs a literal byte to the destination buffer including the + * appropriate control bit. + * ---------- + */ +#define pgrb_out_literal(_ctrlp,_ctrlb,_ctrl,_buf,_byte) \ +do { \ + pgrb_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ + *(_buf)++ = (unsigned char)(_byte); \ + _ctrl <<= 1; \ +} while (0) + + +/* ---------- + * pgrb_out_tag - + * + * Outputs a backward reference tag of 2-4 bytes (depending on + * offset and length) to the destination buffer including the + * appropriate control bit. + * ---------- + */ +#define pgrb_out_tag(_ctrlp,_ctrlb,_ctrl,_buf,_len,_off) \ +do { \ + pgrb_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ + _ctrlb |= _ctrl; \ + _ctrl <<= 1; \ + if (_len > 17) \ + { \ + (_buf)[0] = (unsigned char)((((_off) & 0xf00) >> 4) | 0x0f); \ + (_buf)[1] = (unsigned char)(((_off) & 0xff)); \ + (_buf)[2] = (unsigned char)((_len) - 18); \ + (_buf) += 3; \ + } else { \ + (_buf)[0] = (unsigned char)((((_off) & 0xf00) >> 4) | ((_len) - 3)); \ + (_buf)[1] = (unsigned char)((_off) & 0xff); \ + (_buf) += 2; \ + } \ +} while (0) + + +/* ---------- + * pgrb_find_match - + * + * ---------- + */ +static inline int +pgrb_find_match(int16 *hstart, const char* input_chunk_start, + int16 *lenp, int16 *offp, + const char *hend, int hindex) +{ + PGRB_HistEntry *hent; + int16 hentno; + const char *hp; + const char *ip; + int16 history_chunk_size; + int32 len = 0; + int32 off = 0; + + hentno = hstart[hindex]; + hent = &rb_hist_entries[hentno]; + + while (hent != RB_INVALID_ENTRY_PTR) + { + int32 thisoff; + int32 thislen; + int32 maxlen; + + thislen = 0; + hp = hent->ck_start_pos; + ip = input_chunk_start; + + maxlen = PGRB_MAX_MATCH; + if (hend - hp < maxlen) + maxlen = hend - hp; + + thisoff = hend - hent->ck_start_pos; + if (thisoff >= 0x0fff) + break; + + /* + * first try to match uptil chunksize and if the data is + * same for chunk, then try to match further to get the + * larger match. if there is a match at end of chunk, it + * is possible that further bytes in string will match. + */ + while (*ip == *hp && thislen < maxlen) + { + history_chunk_size = PGRB_CHUNK_SIZE; + while (history_chunk_size > 0) + { + if (*hp++ != *ip++) + break; + else + --history_chunk_size; + } + + /* consider only complete chunk matches. */ + if (history_chunk_size == 0) + thislen += PGRB_CHUNK_SIZE; + } + + /* + * Remember this match as the best (if it is) + */ + if (thislen > len) + { + len = thislen; + off = thisoff; + } + + /* + * Advance to the next history entry + */ + hent = hent->next; + } + + /* + * Return match information only if it results at least in one chunk + * reduction. + */ + if (len >= PGRB_CHUNK_SIZE) + { + *lenp = len; + *offp = off; + return 1; + } + + return 0; +} + +static int +choose_hash_size(int slen) +{ + int hashsz; + + /* + * Experiments suggest that these hash sizes work pretty well. A large + * hash table minimizes collision, but has a higher startup cost. For a + * small input, the startup cost dominates. The table size must be a power + * of two. + */ + if (slen < 128) + hashsz = 512; + else if (slen < 256) + hashsz = 1024; + else if (slen < 512) + hashsz = 2048; + else if (slen < 1024) + hashsz = 4096; + else + hashsz = 8192; + return hashsz; +} + +/* ---------- + * Rabin's Delta Encoding - Compresses source data by referring history. + * + * source is the input data to be compressed + * slen is the length of source data + * history is the data which is used as reference for compression + * hlen is the length of history data + * The encoded result is written to dest, and its length is returned in + * finallen. + * The return value is TRUE if compression succeeded, + * FALSE if not; in the latter case the contents of dest + * are undefined. + * ---------- + */ +bool +pgrb_delta_encode(const char *source, int32 slen, + const char *history, int32 hlen, + char *dest, uint32 *finallen, + const PGRB_Strategy *strategy) +{ + unsigned char *bp = ((unsigned char *) dest); + unsigned char *bstart = bp; + const char *dp = source; + const char *dend = source + slen; + const char *dp_unmatched_chunk_start; + const char *dp_unmatched_start; + const char *hp = history; + const char *hend = history + hlen; + unsigned char ctrl_dummy = 0; + unsigned char *ctrlp = &ctrl_dummy; + unsigned char ctrlb = 0; + unsigned char ctrl = 0; + bool unmatched_data = false; + int16 match_len = 0; + int16 match_off; + int32 result_size; + int32 result_max; + int32 result_min; + int32 need_rate; + int hist_next = 1; + int hashsz; + int mask; + int32 hindex; + int16 skip_bytes = 4; + + /* + * Tuples of length greater than PGRB_HISTORY_SIZE are not allowed for + * delta encode as this is the maximum size of history offset. + */ + if (hlen >= PGRB_HISTORY_SIZE || hlen < 4) + return false; + + /* + * Our fallback strategy is the default. + */ + if (strategy == NULL) + strategy = PGRB_strategy_default; + + /* + * If the strategy forbids compression (at all or if source chunk size out + * of range), fail. + */ + if (strategy->match_size_good <= 0 || + slen < strategy->min_input_size || + slen > strategy->max_input_size) + return false; + + need_rate = strategy->min_comp_rate; + if (need_rate < 0) + need_rate = 0; + else if (need_rate > 99) + need_rate = 99; + + /* + * Compute the maximum result size allowed by the strategy, namely the + * input size minus the minimum wanted compression rate. This had better + * be <= slen, else we might overrun the provided output buffer. + */ + if (slen > (INT_MAX / 100)) + { + /* Approximate to avoid overflow */ + result_max = (slen / 100) * (100 - need_rate); + result_min = (slen / 100) * need_rate; + } + else + { + result_max = (slen * (100 - need_rate)) / 100; + result_min = (slen * (need_rate)) / 100; + } + + hashsz = choose_hash_size(hlen/PGRB_CHUNK_SIZE); + mask = hashsz - 1; + + /* + * Initialize the history lists to empty. We do not need to zero the + * rb_hist_entries[] array; its entries are initialized as they are used. + */ + memset(hist_start, 0, hashsz * sizeof(int16)); + + /* + * Form the history table using fixed PGRB_CHUNK_SIZE bytes. + */ + while (hp < hend - 4) + { + hindex = pgrb_hist_idx(hp, mask); + pgrb_hist_add_no_recycle(hist_start, rb_hist_entries, + hist_next, hp, hindex); + hp += PGRB_CHUNK_SIZE; + } + + /* + * Loop through the input. We do this in two passes, in first pass + * it loops till first match is found and after that whole tuple + * is processed in second pass. This is to optimize the encoding so + * that we don't need to copy any unmatched bytes till we find a + * match. + */ + match_off = 0; + dp_unmatched_chunk_start = dp; + dp_unmatched_start = dp; + pgrb_hash_init(dp, hindex); + /* Pass - 1 */ + while (dp < dend - 4) + { + /* + * If we don't find any match till result minimum size, + * then fall out. + */ + if (dend - dp <= result_min) + return false; + + /* + * Try to find a match in the history + */ + pgrb_hash_roll(dp, hindex); + + if (pgrb_find_match(hist_start, dp, + &match_len, &match_off, + hend, (hindex & mask))) + { + /* + * Create the tag and add history entries for all matched + * characters and ensure to copy any unmatched data till + * this point. Currently this code only delays copy of + * unmatched data in begining. + */ + while (dp_unmatched_start < dp) + { + pgrb_out_literal(ctrlp, ctrlb, ctrl, bp, *dp_unmatched_start); + dp_unmatched_start++; + } + pgrb_out_tag(ctrlp, ctrlb, ctrl, bp, match_len, match_off); + pgrb_hash_unroll(dp, hindex); + dp += match_len; + break; + } + pgrb_hash_unroll(dp, hindex); + + /* + * If we don't find any match for first 4 bytes, then skip 4 bytes + * and if we don't find match again for next 8 bytes, then skip 8 + * bytes and keep on doing the same until we find first match. + * There is a chance that we miss some bytes for compression, but + * it should not effect much as we are doing this only till we find + * first match. + */ + if (dp - dp_unmatched_chunk_start >= skip_bytes) + { + dp += skip_bytes; + dp_unmatched_chunk_start = dp; + skip_bytes *= 2; + } + else + dp++; + } + + /* Pass - 2 */ + while (dp < dend - 4) + { + /* If we already exceeded the maximum result size, fail. */ + if (bp - bstart >= result_max) + return false; + + /* + * Try to find a match in the history + */ + pgrb_hash_roll(dp, hindex); + + if (pgrb_find_match(hist_start, dp, + &match_len, &match_off, + hend, (hindex & mask))) + { + /* + * Create the tag and add history entries for all matched + * characters. + */ + pgrb_out_tag(ctrlp, ctrlb, ctrl, bp, match_len, match_off); + pgrb_hash_unroll(dp, hindex); + dp += match_len; + } + else + { + /* No match found, copy literal byte into destination buffer. */ + pgrb_out_literal(ctrlp, ctrlb, ctrl, bp, *dp); + pgrb_hash_unroll(dp, hindex); + dp++; + } + } + + /* Handle the last few bytes as literals */ + while (dp < dend) + { + pgrb_out_literal(ctrlp, ctrlb, ctrl, bp, *dp); + dp++; /* Do not do this ++ in the line above! */ + } + + /* + * Write out the last control byte and check that we haven't overrun the + * output size allowed by the strategy. + */ + *ctrlp = ctrlb; + result_size = bp - bstart; + +#ifdef DELTA_DEBUG + elog(LOG, "old %d new %d compressed %d", hlen, slen, result_size); +#endif + + /* + * Success - need only fill in the actual length of the compressed datum. + */ + *finallen = result_size; + + return true; +} + +/* ---------- + * pgrb_delta_decode + * + * Decompresses source into dest. + * ---------- + */ +void +pgrb_delta_decode(const char *source, uint32 srclen, + char *dest, uint32 destlen, uint32 *finallen, + const char *history, uint32 histlen) +{ + const unsigned char *sp; + const unsigned char *srcend; + unsigned char *dp; + unsigned char *destend; + const char *hend; + + sp = ((const unsigned char *) source); + srcend = ((const unsigned char *) source) + srclen; + dp = (unsigned char *) dest; + destend = dp + destlen; + hend = history + histlen; + + while (sp < srcend && dp < destend) + { + /* + * Read one control byte and process the next 8 items (or as many as + * remain in the compressed input). + */ + unsigned char ctrl = *sp++; + int ctrlc; + + for (ctrlc = 0; ctrlc < 8 && sp < srcend; ctrlc++) + { + if (ctrl & 1) + { + /* + * Otherwise it contains the match length minus 3 and the + * upper 4 bits of the offset. The next following byte + * contains the lower 8 bits of the offset. If the length is + * coded as 18, another extension tag byte tells how much + * longer the match really was (0-255). + */ + int32 len; + int32 off; + + len = (sp[0] & 0x0f) + 3; + off = ((sp[0] & 0xf0) << 4) | sp[1]; + sp += 2; + if (len == 18) + len += *sp++; + + /* + * Check for output buffer overrun, to ensure we don't clobber + * memory in case of corrupt input. Note: we must advance dp + * here to ensure the error is detected below the loop. We + * don't simply put the elog inside the loop since that will + * probably interfere with optimization. + */ + if (dp + len > destend) + { + dp += len; + break; + } + + /* + * Now we copy the bytes specified by the tag from history to + * OUTPUT. We can safely use memcpy here because source and + * destination strings will not overlap as in case of LZ. + */ + memcpy(dp, hend - off, len); + dp += len; + } + else + { + /* + * An unset control bit means LITERAL BYTE. So we just copy + * one from INPUT to OUTPUT. + */ + if (dp >= destend) /* check for buffer overrun */ + break; /* do not clobber memory */ + + *dp++ = *sp++; + } + + /* + * Advance the control bit + */ + ctrl >>= 1; + } + } + + /* + * Check we decompressed the right amount. + */ + if (sp != srcend) + elog(PANIC, "compressed data is corrupt"); + + /* + * That's it. + */ + *finallen = ((char *) dp - dest); +} diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h index d4383ab..df64096 100644 --- a/src/include/access/heapam_xlog.h +++ b/src/include/access/heapam_xlog.h @@ -67,6 +67,7 @@ #define XLOG_HEAP_CONTAINS_OLD_TUPLE (1<<2) #define XLOG_HEAP_CONTAINS_OLD_KEY (1<<3) #define XLOG_HEAP_CONTAINS_NEW_TUPLE (1<<4) +#define XLOG_HEAP_DELTA_ENCODED (1<<5) /* convenience macro for checking whether any form of old tuple was logged */ #define XLOG_HEAP_CONTAINS_OLD \ diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h index a3eba98..abb5620 100644 --- a/src/include/access/htup_details.h +++ b/src/include/access/htup_details.h @@ -740,6 +740,11 @@ extern HeapTuple heap_modify_tuple(HeapTuple tuple, extern void heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc, Datum *values, bool *isnull); +extern bool heap_delta_encode(TupleDesc tupleDesc, HeapTuple oldtup, + HeapTuple newtup, char *encdata, uint32 *enclen); +extern void heap_delta_decode (char *encdata, uint32 enclen, HeapTuple oldtup, + HeapTuple newtup); + /* these three are deprecated versions of the three above: */ extern HeapTuple heap_formtuple(TupleDesc tupleDescriptor, Datum *values, char *nulls); diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 47e3022..51d6925 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -279,6 +279,7 @@ typedef struct CheckpointStatsData extern CheckpointStatsData CheckpointStats; extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata); +extern bool XLogCheckBufferNeedsBackup(Buffer buffer); extern void XLogFlush(XLogRecPtr RecPtr); extern bool XLogBackgroundFlush(void); extern bool XLogNeedsFlush(XLogRecPtr RecPtr); diff --git a/src/include/utils/pg_rbcompress.h b/src/include/utils/pg_rbcompress.h new file mode 100644 index 0000000..84f154d --- /dev/null +++ b/src/include/utils/pg_rbcompress.h @@ -0,0 +1,79 @@ +/* ---------- + * pg_rbcompress.h - + * + * Definitions for the builtin Rabin compressor + * + * src/include/utils/pg_rbcompress.h + * ---------- + */ + +#ifndef _PG_RBCOMPRESS_H_ +#define _PG_RBCOMPRESS_H_ + + +/* ---------- + * PGRB_Strategy - + * + * Some values that control the compression algorithm. + * + * min_input_size Minimum input data size to consider compression. + * + * max_input_size Maximum input data size to consider compression. + * + * min_comp_rate Minimum compression rate (0-99%) to require. + * Regardless of min_comp_rate, the output must be + * smaller than the input, else we don't store + * compressed. + * + * first_success_by Abandon compression if we find no compressible + * data within the first this-many bytes. + * + * match_size_good The initial GOOD match size when starting history + * lookup. When looking up the history to find a + * match that could be expressed as a tag, the + * algorithm does not always walk back entirely. + * A good match fast is usually better than the + * best possible one very late. For each iteration + * in the lookup, this value is lowered so the + * longer the lookup takes, the smaller matches + * are considered good. + * + * match_size_drop The percentage by which match_size_good is lowered + * after each history check. Allowed values are + * 0 (no change until end) to 100 (only check + * latest history entry at all). + * ---------- + */ +typedef struct PGRB_Strategy +{ + int32 min_input_size; + int32 max_input_size; + int32 min_comp_rate; + int32 first_success_by; + int32 match_size_good; + int32 match_size_drop; +} PGRB_Strategy; + + +/* ---------- + * The standard strategies + * + * PGRB_strategy_default Recommended default strategy for WAL + * compression. + * ---------- + */ +extern const PGRB_Strategy *const PGRB_strategy_default; + + +/* ---------- + * Global function declarations + * ---------- + */ +extern bool pgrb_delta_encode(const char *source, int32 slen, + const char *history, int32 hlen, + char *dest, uint32 *finallen, const PGRB_Strategy *strategy); +extern void pgrb_delta_decode(const char *source, uint32 srclen, + char *dest, uint32 destlen, uint32 *finallen, + const char *history, uint32 histlen); + +#endif /* _PG_RBCOMPRESS_H_ */ diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index 9b8a4c9..717b90b 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -218,6 +218,7 @@ typedef struct StdRdOptions bool security_barrier; /* for views */ int check_option_offset; /* for views */ bool user_catalog_table; /* use as an additional catalog relation */ + bool wal_compress_update; /* compress wal tuple for update */ } StdRdOptions; #define HEAP_MIN_FILLFACTOR 10 @@ -296,6 +297,15 @@ typedef struct StdRdOptions ((StdRdOptions *) (relation)->rd_options)->user_catalog_table : false) /* + * RelationIsEnabledForWalCompression + * Returns whether the wal for update operation on relation can + * be compressed. + */ +#define RelationIsEnabledForWalCompression(relation) \ + ((relation)->rd_options ? \ + ((StdRdOptions *) (relation)->rd_options)->wal_compress_update : true) + +/* * RelationIsValid * True iff relation descriptor is valid. */ diff --git a/src/test/regress/expected/update.out b/src/test/regress/expected/update.out index 71b856f..af46df2 100644 --- a/src/test/regress/expected/update.out +++ b/src/test/regress/expected/update.out @@ -97,3 +97,73 @@ SELECT a, b, char_length(c) FROM update_test; (2 rows) DROP TABLE update_test; +-- +-- Test to update continuos and non continuos columns +-- +DROP TABLE IF EXISTS update_test; +NOTICE: table "update_test" does not exist, skipping +CREATE TABLE update_test ( + bser bigserial, + bln boolean, + ename VARCHAR(25), + perf_f float(8), + grade CHAR, + dept CHAR(5) NOT NULL, + dob DATE, + idnum INT, + addr VARCHAR(30) NOT NULL, + destn CHAR(6), + Gend CHAR, + samba BIGINT, + hgt float, + ctime TIME +); +INSERT INTO update_test VALUES ( + nextval('update_test_bser_seq'::regclass), + TRUE, + 'Test', + 7.169, + 'B', + 'CSD', + '2000-01-01', + 520, + 'road2, + streeeeet2, + city2', + 'dcy2', + 'M', + 12000, + 50.4, + '00:00:00.0' +); +SELECT * from update_test; + bser | bln | ename | perf_f | grade | dept | dob | idnum | addr | destn | gend | samba | hgt | ctime +------+-----+-------+--------+-------+-------+------------+-------+-----------------------------+--------+------+-------+------+---------- + 1 | t | Test | 7.169 | B | CSD | 01-01-2000 | 520 | road2, +| dcy2 | M | 12000 | 50.4 | 00:00:00 + | | | | | | | | streeeeet2,+| | | | | + | | | | | | | | city2 | | | | | +(1 row) + +-- update first column +UPDATE update_test SET bser = bser - 1 + 1; +-- update middle column +UPDATE update_test SET perf_f = 8.9; +-- update last column +UPDATE update_test SET ctime = '00:00:00.1'; +-- update 3 continuos columns +UPDATE update_test SET destn = 'dcy2', samba = 0 WHERE Gend = 'M' and dept = 'CSD'; +-- update two non continuos columns +UPDATE update_test SET destn = 'moved', samba = 0; +UPDATE update_test SET bln = FALSE, hgt = 10.1; +-- update causing some column alignment difference +UPDATE update_test SET ename = 'Tes'; +UPDATE update_test SET dept = 'Test'; +SELECT * from update_test; + bser | bln | ename | perf_f | grade | dept | dob | idnum | addr | destn | gend | samba | hgt | ctime +------+-----+-------+--------+-------+-------+------------+-------+-----------------------------+--------+------+-------+------+------------ + 1 | f | Tes | 8.9 | B | Test | 01-01-2000 | 520 | road2, +| moved | M | 0 | 10.1 | 00:00:00.1 + | | | | | | | | streeeeet2,+| | | | | + | | | | | | | | city2 | | | | | +(1 row) + +DROP TABLE update_test; diff --git a/src/test/regress/sql/update.sql b/src/test/regress/sql/update.sql index a8a028f..1806992 100644 --- a/src/test/regress/sql/update.sql +++ b/src/test/regress/sql/update.sql @@ -59,3 +59,70 @@ UPDATE update_test SET c = repeat('x', 10000) WHERE c = 'car'; SELECT a, b, char_length(c) FROM update_test; DROP TABLE update_test; + + +-- +-- Test to update continuos and non continuos columns +-- + +DROP TABLE IF EXISTS update_test; +CREATE TABLE update_test ( + bser bigserial, + bln boolean, + ename VARCHAR(25), + perf_f float(8), + grade CHAR, + dept CHAR(5) NOT NULL, + dob DATE, + idnum INT, + addr VARCHAR(30) NOT NULL, + destn CHAR(6), + Gend CHAR, + samba BIGINT, + hgt float, + ctime TIME +); + +INSERT INTO update_test VALUES ( + nextval('update_test_bser_seq'::regclass), + TRUE, + 'Test', + 7.169, + 'B', + 'CSD', + '2000-01-01', + 520, + 'road2, + streeeeet2, + city2', + 'dcy2', + 'M', + 12000, + 50.4, + '00:00:00.0' +); + +SELECT * from update_test; + +-- update first column +UPDATE update_test SET bser = bser - 1 + 1; + +-- update middle column +UPDATE update_test SET perf_f = 8.9; + +-- update last column +UPDATE update_test SET ctime = '00:00:00.1'; + +-- update 3 continuos columns +UPDATE update_test SET destn = 'dcy2', samba = 0 WHERE Gend = 'M' and dept = 'CSD'; + +-- update two non continuos columns +UPDATE update_test SET destn = 'moved', samba = 0; +UPDATE update_test SET bln = FALSE, hgt = 10.1; + +-- update causing some column alignment difference +UPDATE update_test SET ename = 'Tes'; +UPDATE update_test SET dept = 'Test'; + +SELECT * from update_test; +DROP TABLE update_test;