diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c index e39b977..875434d 100644 --- a/src/backend/access/common/heaptuple.c +++ b/src/backend/access/common/heaptuple.c @@ -60,7 +60,11 @@ #include "access/sysattr.h" #include "access/tuptoaster.h" #include "executor/tuptable.h" +#include "utils/datum.h" +#include "utils/pg_lzcompress.h" +/* guc variable for EWT compression ratio*/ +int wal_update_compression_ratio = 25; /* Does att's datatype allow packing into the 1-byte-header varlena format? */ #define ATT_IS_PACKABLE(att) \ @@ -617,6 +621,49 @@ 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, using pglz. The result is + * stored in *encdata. *encdata must point to a PGLZ_header buffer, with at + * least PGLZ_MAX_OUTPUT(newtup->t_len) bytes. + * ---------------- + */ +bool +heap_delta_encode(TupleDesc tupleDesc, HeapTuple oldtup, HeapTuple newtup, + char *encdata, uint32 *enclen) +{ + PGLZ_Strategy strategy; + + strategy = *PGLZ_strategy_default; + strategy.min_comp_rate = wal_update_compression_ratio; + + return pglz_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, &strategy + ); +} + +/* ---------------- + * 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) +{ + return pglz_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/heap/heapam.c b/src/backend/access/heap/heapam.c index 5bcbc92..6dc362e 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -70,10 +70,12 @@ #include "utils/snapmgr.h" #include "utils/syscache.h" #include "utils/tqual.h" +#include "utils/pg_lzcompress.h" /* GUC variable */ bool synchronize_seqscans = true; +extern int wal_update_compression_ratio; static HeapScanDesc heap_beginscan_internal(Relation relation, @@ -5844,6 +5846,12 @@ log_heap_update(Relation reln, Buffer oldbuf, XLogRecPtr recptr; XLogRecData rdata[4]; Page page = BufferGetPage(newbuf); + char *newtupdata; + int newtuplen; + bool compressed = false; + + /* Structure which holds EWT */ + char buf[MaxHeapTupleSize]; /* Caller should not call me on a non-WAL-logged relation */ Assert(RelationNeedsWAL(reln)); @@ -5853,15 +5861,48 @@ 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 bolck in + * WAL as in that case there is no saving by reduced WAL size. + */ + if (wal_update_compression_ratio != 0 && (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.flags = 0; xlrec.target.node = reln->rd_node; xlrec.target.tid = oldtup->t_self; xlrec.old_xmax = HeapTupleHeaderGetRawXmax(oldtup->t_data); xlrec.old_infobits_set = compute_infobits(oldtup->t_data->t_infomask, oldtup->t_data->t_infomask2); xlrec.new_xmax = HeapTupleHeaderGetRawXmax(newtup->t_data); - xlrec.all_visible_cleared = all_visible_cleared; + if (all_visible_cleared) + xlrec.flags |= XL_HEAP_UPDATE_ALL_VISIBLE_CLEARED; xlrec.newtid = newtup->t_self; - xlrec.new_all_visible_cleared = new_all_visible_cleared; + if (new_all_visible_cleared) + xlrec.flags |= XL_HEAP_UPDATE_NEW_ALL_VISIBLE_CLEARED; + if (compressed) + xlrec.flags |= XL_HEAP_UPDATE_DELTA_ENCODED; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapUpdate; @@ -5888,9 +5929,12 @@ 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 follows ......... + * OR PG94FORMAT [If encoded]: LZ header + Encoded data follows + */ + rdata[3].data = newtupdata; + rdata[3].len = newtuplen; rdata[3].buffer = newbuf; rdata[3].buffer_std = true; rdata[3].next = NULL; @@ -6700,7 +6744,10 @@ 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; @@ -6715,7 +6762,7 @@ heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool hot_update) * The visibility map may need to be fixed even if the heap page is * already up-to-date. */ - if (xlrec->all_visible_cleared) + if (xlrec->flags & XL_HEAP_UPDATE_ALL_VISIBLE_CLEARED) { Relation reln = CreateFakeRelcacheEntry(xlrec->target.node); BlockNumber block = ItemPointerGetBlockNumber(&xlrec->target.tid); @@ -6775,7 +6822,7 @@ 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; @@ -6793,7 +6840,7 @@ heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool hot_update) /* Mark the page as a candidate for pruning */ PageSetPrunable(page, record->xl_xid); - if (xlrec->all_visible_cleared) + if (xlrec->flags & XL_HEAP_UPDATE_ALL_VISIBLE_CLEARED) PageClearAllVisible(page); /* @@ -6817,7 +6864,7 @@ newt:; * The visibility map may need to be fixed even if the heap page is * already up-to-date. */ - if (xlrec->new_all_visible_cleared) + if (xlrec->flags & XL_HEAP_UPDATE_NEW_ALL_VISIBLE_CLEARED) { Relation reln = CreateFakeRelcacheEntry(xlrec->target.node); BlockNumber block = ItemPointerGetBlockNumber(&xlrec->newtid); @@ -6884,10 +6931,31 @@ newsame:; SizeOfHeapHeader); 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 & XL_HEAP_UPDATE_DELTA_ENCODED) + { + /* + * PG94FORMAT: Header + 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.t_infomask2; htup->t_infomask = xlhdr.t_infomask; @@ -6903,7 +6971,7 @@ newsame:; if (offnum == InvalidOffsetNumber) elog(PANIC, "heap_update_redo: failed to add tuple"); - if (xlrec->new_all_visible_cleared) + if (xlrec->flags & XL_HEAP_UPDATE_NEW_ALL_VISIBLE_CLEARED) PageClearAllVisible(page); freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */ diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 96aceb9..fed305d 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2308,6 +2308,28 @@ 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 WAL 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/pg_lzcompress.c b/src/backend/utils/adt/pg_lzcompress.c index 1c129b8..cbf6064 100644 --- a/src/backend/utils/adt/pg_lzcompress.c +++ b/src/backend/utils/adt/pg_lzcompress.c @@ -120,7 +120,7 @@ * matching strings. This is done on the fly while the input * is compressed into the output area. Table entries are only * kept for the last 4096 input positions, since we cannot use - * back-pointers larger than that anyway. The size of the hash + * back-pointers larger than that anyway. The size of the hash * table is chosen based on the size of the input - a larger table * has a larger startup cost, as it needs to be initialized to * zero, but reduces the number of hash collisions on long inputs. @@ -202,7 +202,8 @@ typedef struct PGLZ_HistEntry { struct PGLZ_HistEntry *next; /* links for my hash key's list */ struct PGLZ_HistEntry *prev; - int hindex; /* my current hash key */ + uint32 hindex; /* my current hash key */ + bool from_history; /* Is the hash entry from history buffer? */ const char *pos; /* my input position */ } PGLZ_HistEntry; @@ -265,12 +266,40 @@ static PGLZ_HistEntry hist_entries[PGLZ_HISTORY_SIZE + 1]; * hash keys more. * ---------- */ -#define pglz_hist_idx(_s,_e, _mask) ( \ - ((((_e) - (_s)) < 4) ? (int) (_s)[0] : \ - (((_s)[0] << 6) ^ ((_s)[1] << 4) ^ \ - ((_s)[2] << 2) ^ (_s)[3])) & (_mask) \ +#define pglz_hist_idx(_s,_e, _mask) ( \ + ((((_e) - (_s)) < 4) ? (int) (_s)[0] : \ + (((_s)[0] << 6) ^ ((_s)[1] << 4) ^ \ + ((_s)[2] << 2) ^ (_s)[3])) & (_mask) \ ) +/* + * pglz_hash_init and pglz_hash_roll can be use to calculate the hash in + * a rolling fashion. First, call pglz_hash_init, with a pointer to the first + * byte. Then call pglz_hash_roll for every subsequent byte. After each + * pglz_hash_roll() call, hindex holds the (masked) hash of the current byte. + * + * a,b,c,d are local variables these macros use to store state. These macros + * don't check for end-of-buffer like pglz_hist_idx() does, so these cannot be + * used on the last 3 bytes of input. + */ +#define pglz_hash_init(_p,hindex,a,b,c,d) \ + do { \ + a = 0; \ + b = _p[0]; \ + c = _p[1]; \ + d = _p[2]; \ + hindex = (b << 4) ^ (c << 2) ^ d; \ + } while (0) + +#define pglz_hash_roll(_p,hindex,a,b,c,d,_mask) \ + do { \ + /* subtract old a */ \ + hindex ^= a; \ + /* shift and add byte */ \ + a = b; b = c; c = d; d = _p[3]; \ + hindex = ((hindex << 2) ^ d) & (_mask); \ + } while (0) + /* ---------- * pglz_hist_add - @@ -284,10 +313,9 @@ static PGLZ_HistEntry hist_entries[PGLZ_HISTORY_SIZE + 1]; * _hn and _recycle are modified in the macro. * ---------- */ -#define pglz_hist_add(_hs,_he,_hn,_recycle,_s,_e, _mask) \ +#define pglz_hist_add(_hs,_he,_hn,_recycle,_s,_e, _hindex) \ do { \ - int __hindex = pglz_hist_idx((_s),(_e), (_mask)); \ - int16 *__myhsp = &(_hs)[__hindex]; \ + int16 *__myhsp = &(_hs)[_hindex]; \ PGLZ_HistEntry *__myhe = &(_he)[_hn]; \ if (_recycle) { \ if (__myhe->prev == NULL) \ @@ -299,7 +327,7 @@ do { \ } \ __myhe->next = &(_he)[*__myhsp]; \ __myhe->prev = NULL; \ - __myhe->hindex = __hindex; \ + __myhe->hindex = _hindex; \ __myhe->pos = (_s); \ /* If there was an existing entry in this hash slot, link */ \ /* this new entry to it. However, the 0th entry in the */ \ @@ -317,6 +345,23 @@ do { \ } \ } while (0) +/* + * An version of pglz_hist_add() that doesn't do recycling. Can be used if + * you know the input fits in PGLZ_HISTORY_SIZE. + */ +#define pglz_hist_add_no_recycle(_hs,_he,_hn,_s,_e, _hindex, _from_history) \ +do { \ + int16 *__myhsp = &(_hs)[_hindex]; \ + PGLZ_HistEntry *__myhe = &(_he)[_hn]; \ + __myhe->next = &(_he)[*__myhsp]; \ + __myhe->prev = NULL; \ + __myhe->hindex = _hindex; \ + __myhe->pos = (_s); \ + (_he)[(*__myhsp)].prev = __myhe; \ + *__myhsp = _hn; \ + ++(_hn); \ + __myhe->from_history = _from_history; \ +} while (0) /* ---------- * pglz_out_ctrl - @@ -379,6 +424,49 @@ do { \ /* ---------- + * pglz_out_tag_encode - + * + * Outputs a backward reference tag of 2-4 bytes (depending on + * offset and length) to the destination/history buffer including the + * appropriate control bit. + * ---------- + */ +#define pglz_out_tag_encode(_ctrlp,_ctrlb,_ctrl,_buf,_len,_off,_from_history) \ +do { \ + pglz_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ + _ctrlb |= _ctrl; \ + _ctrl <<= 1; \ + if (_from_history) \ + _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) + +/* ---------- + * pglz_out_literal_encode - + * + * Outputs a literal byte to the destination buffer including the + * appropriate control bit. + * ---------- + */ +#define pglz_out_literal_encode(_ctrlp,_ctrlb,_ctrl,_buf,_byte) \ +do { \ + pglz_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ + *(_buf)++ = (unsigned char)(_byte); \ + _ctrl <<= 2; \ +} while (0) + +/* ---------- * pglz_find_match - * * Lookup the history table if the actual input stream matches @@ -388,17 +476,21 @@ do { \ */ static inline int pglz_find_match(int16 *hstart, const char *input, const char *end, - int *lenp, int *offp, int good_match, int good_drop, int mask) + int *lenp, int *offp, int good_match, int good_drop, + const char *hend, int hindex, bool *from_history) { PGLZ_HistEntry *hent; int16 hentno; int32 len = 0; int32 off = 0; + bool history_match = false; + + *from_history = false; /* * Traverse the linked history list until a good enough match is found. */ - hentno = hstart[pglz_hist_idx(input, end, mask)]; + hentno = hstart[hindex]; hent = &hist_entries[hentno]; while (hent != INVALID_ENTRY_PTR) { @@ -406,11 +498,26 @@ pglz_find_match(int16 *hstart, const char *input, const char *end, const char *hp = hent->pos; int32 thisoff; int32 thislen; + int32 maxlen; + + history_match = false; + maxlen = PGLZ_MAX_MATCH; + if (hent->from_history && (hend - hp < maxlen)) + maxlen = hend - hp; + else if (end - input < maxlen) + maxlen = end - input; /* * Stop if the offset does not fit into our tag anymore. */ - thisoff = ip - hp; + if (hent->from_history) + { + history_match = true; + thisoff = hend - hp; + } + else + thisoff = ip - hp; + if (thisoff >= 0x0fff) break; @@ -430,7 +537,7 @@ pglz_find_match(int16 *hstart, const char *input, const char *end, thislen = len; ip += len; hp += len; - while (ip < end && *ip == *hp && thislen < PGLZ_MAX_MATCH) + while (*ip == *hp && thislen < maxlen) { thislen++; ip++; @@ -440,7 +547,7 @@ pglz_find_match(int16 *hstart, const char *input, const char *end, } else { - while (ip < end && *ip == *hp && thislen < PGLZ_MAX_MATCH) + while (*ip == *hp && thislen < maxlen) { thislen++; ip++; @@ -453,6 +560,7 @@ pglz_find_match(int16 *hstart, const char *input, const char *end, */ if (thislen > len) { + *from_history = history_match; len = thislen; off = thisoff; } @@ -488,6 +596,29 @@ pglz_find_match(int16 *hstart, const char *input, const char *end, 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; +} /* ---------- * pglz_compress - @@ -574,11 +705,14 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, else result_max = (slen * (100 - need_rate)) / 100; + hashsz = choose_hash_size(slen); + mask = hashsz - 1; + /* * 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. + * 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; @@ -603,6 +737,9 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, */ while (dp < dend) { + uint32 hindex; + bool from_history; + /* * If we already exceeded the maximum result size, fail. * @@ -625,8 +762,10 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, /* * Try to find a match in the history */ + hindex = pglz_hist_idx(dp, dend, mask); if (pglz_find_match(hist_start, dp, dend, &match_len, - &match_off, good_match, good_drop, mask)) + &match_off, good_match, good_drop, NULL, hindex, + &from_history)) { /* * Create the tag and add history entries for all matched @@ -635,9 +774,10 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, pglz_out_tag(ctrlp, ctrlb, ctrl, bp, match_len, match_off); while (match_len--) { + hindex = pglz_hist_idx(dp, dend, mask); pglz_hist_add(hist_start, hist_entries, hist_next, hist_recycle, - dp, dend, mask); + dp, dend, hindex); dp++; /* Do not do this ++ in the line above! */ /* The macro would do it four times - Jan. */ } @@ -651,7 +791,7 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, pglz_out_literal(ctrlp, ctrlb, ctrl, bp, *dp); pglz_hist_add(hist_start, hist_entries, hist_next, hist_recycle, - dp, dend, mask); + dp, dend, hindex); dp++; /* Do not do this ++ in the line above! */ /* The macro would do it four times - Jan. */ } @@ -674,6 +814,209 @@ pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, return true; } +/* + * Delta encoding. + * + * The 'source' is encoded using the same pglz algorithm used for compression. + * The difference with pglz_compress is that the back-references refer to + * the 'history', instead of earlier offsets in 'source'. + * + * The encoded result is written to *dest, and its length is returned in + * *finallen. + */ +bool +pglz_delta_encode(const char *source, int32 slen, + const char *history, int32 hlen, + char *dest, uint32 *finallen, + const PGLZ_Strategy *strategy) +{ + unsigned char *bp = ((unsigned char *) dest); + unsigned char *bstart = bp; + const char *dp = source; + const char *dend = source + slen; + 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 found_match = false; + int32 match_len = 0; + int32 match_off; + int32 result_size; + int32 result_max; + int32 good_match; + int32 good_drop; + int32 need_rate; + int hist_next = 0; + int hashsz; + int mask; + int32 a, + b, + c, + d; + int32 hindex; + + /* + * Tuples of source and history length greater than 2 * PGLZ_HISTORY_SIZE + * are not allowed for delta encode as this is the maximum size of history + * offset. And also tuples with history data less than 4 are not allowed. + */ + if (((hlen + slen) >= (2 * PGLZ_HISTORY_SIZE)) || hlen < 4) + return false; + + /* + * Our fallback strategy is the default. + */ + if (strategy == NULL) + strategy = PGLZ_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; + + /* + * Limit the match parameters to the supported range. + */ + good_match = strategy->match_size_good; + if (good_match > PGLZ_MAX_MATCH) + good_match = PGLZ_MAX_MATCH; + else if (good_match < 17) + good_match = 17; + + good_drop = strategy->match_size_drop; + if (good_drop < 0) + good_drop = 0; + else if (good_drop > 100) + good_drop = 100; + + /* + * 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); + } + else + result_max = (slen * (100 - need_rate)) / 100; + + hashsz = choose_hash_size(hlen + slen); + mask = hashsz - 1; + + /* + * Initialize the history lists to empty. We do not need to zero the + * hist_entries[] array; its entries are initialized as they are used. + */ + memset(hist_start, 0, hashsz * sizeof(int16)); + + pglz_hash_init(hp, hindex, a, b, c, d); + while (hp < hend - 4) + { + /* + * TODO: It would be nice to behave like the history and the source + * strings were concatenated, so that you could compress using the new + * data, too. + */ + pglz_hash_roll(hp, hindex, a, b, c, d, mask); + pglz_hist_add_no_recycle(hist_start, hist_entries, + hist_next, + hp, hend, hindex, true); + hp++; /* Do not do this ++ in the line above! */ + } + + /* + * Loop through the input. + */ + match_off = 0; + pglz_hash_init(dp, hindex, a, b, c, d); + while (dp < dend - 4) + { + bool from_history; + + /* + * If we already exceeded the maximum result size, fail. + * + * We check once per loop; since the loop body could emit as many as 4 + * bytes (a control byte and 3-byte tag), PGLZ_MAX_OUTPUT() had better + * allow 4 slop bytes. + */ + if (bp - bstart >= result_max) + return false; + + /* + * Try to find a match in the history + */ + pglz_hash_roll(dp, hindex, a, b, c, d, mask); + if (pglz_find_match(hist_start, dp, dend, &match_len, + &match_off, good_match, good_drop, hend, hindex, + &from_history)) + { + /* + * Create the tag and add history entries for all matched + * characters. + */ + pglz_out_tag_encode(ctrlp, ctrlb, ctrl, bp, match_len, match_off, from_history); + dp += match_len; + found_match = true; + pglz_hash_init(dp, hindex, a, b, c, d); + } + else + { + /* + * No match found. Copy one literal byte. + */ + pglz_hist_add_no_recycle(hist_start, hist_entries, + hist_next, + dp, dend, hindex, false); + + pglz_out_literal_encode(ctrlp, ctrlb, ctrl, bp, *dp); + dp++; /* Do not do this ++ in the line above! */ + /* The macro would do it four times - Jan. */ + } + } + + if (!found_match) + return false; + + /* Handle the last few bytes as literals */ + while (dp < dend) + { + pglz_out_literal_encode(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; +} /* ---------- * pglz_decompress - @@ -777,3 +1120,124 @@ pglz_decompress(const PGLZ_Header *source, char *dest) * That's it. */ } + +/* ---------- + * pglz_delta_decode + * + * Decompresses source into dest. + * To decompress, it uses history if provided. + * ---------- + */ +void +pglz_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 += 2) + { + 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. + */ + if ((ctrl >> 1) & 1) + { + memcpy(dp, hend - off, len); + dp += len; + } + else + { + /* + * Now we copy the bytes specified by the tag from OUTPUT + * to OUTPUT. It is dangerous and platform dependent to + * use memcpy() here, because the copied areas could + * overlap extremely! + */ + while (len--) + { + *dp = dp[-off]; + dp++; + } + } + } + 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 >>= 2; + } + } + + /* + * 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/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 2b753f8..13ef553 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -125,6 +125,7 @@ extern char *default_tablespace; extern char *temp_tablespaces; extern bool ignore_checksum_failure; extern bool synchronize_seqscans; +extern int wal_update_compression_ratio; extern int ssl_renegotiation_limit; extern char *SSLCipherSuites; @@ -2437,6 +2438,17 @@ static struct config_int ConfigureNamesInt[] = NULL, NULL, NULL }, + { + /* Not for general use */ + {"wal_update_compression_ratio", PGC_USERSET, DEVELOPER_OPTIONS, + gettext_noop("Sets the compression ratio of delta record for wal update"), + NULL, + }, + &wal_update_compression_ratio, + 25, 0, 100, + NULL, NULL, NULL + }, + /* End-of-list marker */ { {NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h index 4381778..36e7dc8 100644 --- a/src/include/access/heapam_xlog.h +++ b/src/include/access/heapam_xlog.h @@ -148,12 +148,21 @@ typedef struct xl_heap_update TransactionId new_xmax; /* xmax of the new tuple */ ItemPointerData newtid; /* new inserted tuple id */ uint8 old_infobits_set; /* infomask bits to set on old tuple */ - bool all_visible_cleared; /* PD_ALL_VISIBLE was cleared */ - bool new_all_visible_cleared; /* same for the page of newtid */ + uint8 flags; /* flag bits, see below */ /* NEW TUPLE xl_heap_header AND TUPLE DATA FOLLOWS AT END OF STRUCT */ } xl_heap_update; -#define SizeOfHeapUpdate (offsetof(xl_heap_update, new_all_visible_cleared) + sizeof(bool)) +#define XL_HEAP_UPDATE_ALL_VISIBLE_CLEARED 0x01 /* Indicates as old + * page's all visible + * bit is cleared */ +#define XL_HEAP_UPDATE_NEW_ALL_VISIBLE_CLEARED 0x02 /* Indicates as new + * page's all visible + * bit is cleared */ +#define XL_HEAP_UPDATE_DELTA_ENCODED 0x04 /* Indicates as the + * update operation is + * delta encoded */ + +#define SizeOfHeapUpdate (offsetof(xl_heap_update, flags) + sizeof(uint8)) /* * This is what we need to know about vacuum page cleanup/redirect diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h index 0a832e9..830349b 100644 --- a/src/include/access/htup_details.h +++ b/src/include/access/htup_details.h @@ -689,6 +689,11 @@ 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 002862c..0a928d9 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -262,6 +262,7 @@ 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_lzcompress.h b/src/include/utils/pg_lzcompress.h index 4af24a3..5add61a 100644 --- a/src/include/utils/pg_lzcompress.h +++ b/src/include/utils/pg_lzcompress.h @@ -107,6 +107,12 @@ extern const PGLZ_Strategy *const PGLZ_strategy_always; */ extern bool pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, const PGLZ_Strategy *strategy); +extern bool pglz_delta_encode(const char *source, int32 slen, + const char *history, int32 hlen, + char *dest, uint32 *finallen, const PGLZ_Strategy *strategy); extern void pglz_decompress(const PGLZ_Header *source, char *dest); +extern void pglz_delta_decode(const char *source, uint32 srclen, + char *dest, uint32 destlen, uint32 *finallen, + const char *history, uint32 histlen); #endif /* _PG_LZCOMPRESS_H_ */ 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;