bigm_gin.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * Portions Copyright (c) 2007-2012, PostgreSQL Global Development Group
   4  *
   5  * Changelog:
   6  *   2013/01/09
   7  *   Support full text search using bigrams.
   8  *   Author: NTT DATA Corporation
   9  *
  10  *-------------------------------------------------------------------------
  11  */
  12 #include "postgres.h"
  13
  14 #include "bigm.h"
  15
  16 #include "access/gin.h"
  17 #include "access/gin_private.h"
  18 #include "access/itup.h"
  19 #include "access/skey.h"
  20 #include "access/tuptoaster.h"
  21 #include "catalog/pg_type.h"
  22 #include "funcapi.h"
  23 #include "mb/pg_wchar.h"
  24 #include "storage/bufmgr.h"
  25 #include "storage/bufpage.h"
  26 #include "tsearch/ts_locale.h"
  27 #include "utils/array.h"
  28 #include "utils/builtins.h"
  29
  30
  31 PG_FUNCTION_INFO_V1(gin_extract_value_bigm);
  32 Datum           gin_extract_value_bigm(PG_FUNCTION_ARGS);
  33
  34 PG_FUNCTION_INFO_V1(gin_extract_query_bigm);
  35 Datum           gin_extract_query_bigm(PG_FUNCTION_ARGS);
  36
  37 PG_FUNCTION_INFO_V1(gin_bigm_consistent);
  38 Datum           gin_bigm_consistent(PG_FUNCTION_ARGS);
  39
  40 PG_FUNCTION_INFO_V1(gin_bigm_compare_partial);
  41 Datum           gin_bigm_compare_partial(PG_FUNCTION_ARGS);
  42
  43 PG_FUNCTION_INFO_V1(pg_gin_pending_stats);
  44 Datum           pg_gin_pending_stats(PG_FUNCTION_ARGS);
  45
  46 Datum
  47 gin_extract_value_bigm(PG_FUNCTION_ARGS)
  48 {
  49         text       *val = (text *) PG_GETARG_TEXT_P(0);
  50         int32      *nentries = (int32 *) PG_GETARG_POINTER(1);
  51         Datum      *entries = NULL;
  52         BIGM       *bgm;
  53         int32           bgmlen;
  54
  55         *nentries = 0;
  56
  57         bgm = generate_bigm(VARDATA(val), VARSIZE(val) - VARHDRSZ);
  58         bgmlen = ARRNELEM(bgm);
  59
  60         if (bgmlen > 0)
  61         {
  62                 bigm       *ptr;
  63                 int32           i;
  64
  65                 *nentries = bgmlen;
  66                 entries = (Datum *) palloc(sizeof(Datum) * bgmlen);
  67
  68                 ptr = GETARR(bgm);
  69                 for (i = 0; i < bgmlen; i++)
  70                 {
  71                         text            *item = cstring_to_text_with_len(ptr->str, ptr->bytelen);
  72                         entries[i] = PointerGetDatum(item);
  73                         ptr++;
  74                 }
  75         }
  76
  77         PG_RETURN_POINTER(entries);
  78 }
  79
  80 Datum
  81 gin_extract_query_bigm(PG_FUNCTION_ARGS)
  82 {
  83         text       *val = (text *) PG_GETARG_TEXT_P(0);
  84         int32      *nentries = (int32 *) PG_GETARG_POINTER(1);
  85         StrategyNumber strategy = PG_GETARG_UINT16(2);
  86
  87         bool   **pmatch = (bool **) PG_GETARG_POINTER(3);
  88         Pointer   **extra_data = (Pointer **) PG_GETARG_POINTER(4);
  89         /* bool   **nullFlags = (bool **) PG_GETARG_POINTER(5); */
  90         int32      *searchMode = (int32 *) PG_GETARG_POINTER(6);
  91         Datum      *entries = NULL;
  92         BIGM       *bgm;
  93         int32           bgmlen = 0;
  94         bigm       *ptr;
  95         int32           i;
  96         bool            removeDups;
  97
  98         switch (strategy)
  99         {
 100                 case LikeStrategyNumber:
 101                 {
 102                         char    *str = VARDATA(val);
 103                         int             slen = VARSIZE(val) - VARHDRSZ;
 104                         bool    *recheck;
 105
 106                         /*
 107                          * For wildcard search we extract all the bigrams that every
 108                          * potentially-matching string must include.
 109                          */
 110                         bgm = generate_wildcard_bigm(str, slen, &removeDups);
 111                         bgmlen = ARRNELEM(bgm);
 112
 113                         /*
 114                          * Check whether the heap tuple fetched by index search needs to be
 115                          * rechecked against the query. If the search word consists of one
 116                          * or two characters and doesn't contain any space character, we can
 117                          * guarantee that the index test would be exact. That is, the heap
 118                          * tuple does match the query, so it doesn't need to be rechecked.
 119                          */
 120                         *extra_data = (Pointer *) palloc(sizeof(bool));
 121                         recheck = (bool *) *extra_data;
 122                         if (bgmlen == 1 && !removeDups)
 123                         {
 124                                 const char      *sp;
 125
 126                                 *recheck = false;
 127                                 for (sp = str; (sp - str) < slen;)
 128                                 {
 129                                         if (t_isspace(sp))
 130                                         {
 131                                                 *recheck = true;
 132                                                 break;
 133                                         }
 134
 135                                         sp += IS_HIGHBIT_SET(*sp) ? pg_mblen(sp) : 1;
 136                                 }
 137                         }
 138                         else
 139                                 *recheck = true;
 140                         break;
 141                 }
 142                 default:
 143                         elog(ERROR, "unrecognized strategy number: %d", strategy);
 144                         bgm = NULL;                     /* keep compiler quiet */
 145                         break;
 146         }
 147
 148         *nentries = (bigm_gin_key_limit == 0) ?
 149                 bgmlen : Min(bigm_gin_key_limit, bgmlen);
 150         *pmatch = NULL;
 151
 152         if (*nentries > 0)
 153         {
 154                 entries = (Datum *) palloc(sizeof(Datum) * *nentries);
 155                 ptr = GETARR(bgm);
 156                 for (i = 0; i < *nentries; i++)
 157                 {
 158                         text            *item;
 159
 160                         if (ptr->pmatch)
 161                         {
 162                                 if (*pmatch == NULL)
 163                                         *pmatch = (bool *) palloc0(sizeof(bool) * *nentries);
 164                                 (*pmatch)[i] = true;
 165                         }
 166                         item = cstring_to_text_with_len(ptr->str, ptr->bytelen);
 167                         entries[i] = PointerGetDatum(item);
 168                         ptr++;
 169                 }
 170         }
 171
 172         /*
 173          * If no bigram was extracted then we have to scan all the index.
 174          */
 175         if (*nentries == 0)
 176                 *searchMode = GIN_SEARCH_MODE_ALL;
 177
 178         PG_RETURN_POINTER(entries);
 179 }
 180
 181 Datum
 182 gin_bigm_consistent(PG_FUNCTION_ARGS)
 183 {
 184         bool       *check = (bool *) PG_GETARG_POINTER(0);
 185         StrategyNumber strategy = PG_GETARG_UINT16(1);
 186
 187         /* text    *query = PG_GETARG_TEXT_P(2); */
 188         int32           nkeys = PG_GETARG_INT32(3);
 189
 190         Pointer   *extra_data = (Pointer *) PG_GETARG_POINTER(4);
 191         bool       *recheck = (bool *) PG_GETARG_POINTER(5);
 192         bool            res;
 193         int32           i;
 194
 195         /*
 196          * Don't recheck the heap tuple against the query if either
 197          * pg_bigm.enable_recheck is disabled or the search word is
 198          * the special one so that the index can return the exact
 199          * result.
 200          */
 201         *recheck = bigm_enable_recheck;
 202         if (nkeys == 1)
 203                 *recheck = *((bool *) extra_data);
 204
 205         switch (strategy)
 206         {
 207                 case LikeStrategyNumber:
 208                         /* Check if all extracted bigrams are presented. */
 209                         res = true;
 210                         for (i = 0; i < nkeys; i++)
 211                         {
 212                                 if (!check[i])
 213                                 {
 214                                         res = false;
 215                                         break;
 216                                 }
 217                         }
 218                         break;
 219                 default:
 220                         elog(ERROR, "unrecognized strategy number: %d", strategy);
 221                         res = false;            /* keep compiler quiet */
 222                         break;
 223         }
 224
 225         PG_RETURN_BOOL(res);
 226 }
 227
 228 Datum
 229 gin_bigm_compare_partial(PG_FUNCTION_ARGS)
 230 {
 231         text    *arg1 = PG_GETARG_TEXT_PP(0);
 232         text    *arg2 = PG_GETARG_TEXT_PP(1);
 233         char    *a1p;
 234         char    *a2p;
 235         int             mblen1;
 236         int             mblen2;
 237         int             res;
 238
 239         a1p = VARDATA_ANY(arg1);
 240         a2p = VARDATA_ANY(arg2);
 241
 242         mblen1 = pg_mblen(a1p);
 243         mblen2 = pg_mblen(a2p);
 244
 245         if (mblen1 != mblen2)
 246                 PG_RETURN_INT32(1);
 247
 248         res = memcmp(a1p, a2p, mblen1) ? 1 : 0;
 249         PG_RETURN_INT32(res);
 250 }
 251
 252 /*
 253  * Report both number of pages and number of heap tuples that
 254  * are in the pending list.
 255  */
 256 Datum
 257 pg_gin_pending_stats(PG_FUNCTION_ARGS)
 258 {
 259         Oid                     indexOid = PG_GETARG_OID(0);
 260         Relation        indexRel;
 261         Buffer          metabuffer;
 262         Page            metapage;
 263         GinMetaPageData *metadata;
 264         Datum           values[2];
 265         bool            isnull[2];
 266         HeapTuple       tuple;
 267         TupleDesc       tupdesc;
 268
 269         /*
 270          * Obtain statistic information from the meta page
 271          */
 272         indexRel = index_open(indexOid, AccessShareLock);
 273         metabuffer = ReadBuffer(indexRel, GIN_METAPAGE_BLKNO);
 274         LockBuffer(metabuffer, GIN_SHARE);
 275         metapage = BufferGetPage(metabuffer);
 276         metadata = GinPageGetMeta(metapage);
 277         index_close(indexRel, AccessShareLock);
 278
 279         /*
 280          * Construct a tuple descriptor for the result row. This must
 281          * match this function's pg_bigm--x.x.sql entry.
 282          */
 283         tupdesc = CreateTemplateTupleDesc(2, false);
 284         TupleDescInitEntry(tupdesc, (AttrNumber) 1,
 285                                            "pages", INT4OID, -1, 0);
 286         TupleDescInitEntry(tupdesc, (AttrNumber) 2,
 287                                            "tuples", INT8OID, -1, 0);
 288         tupdesc = BlessTupleDesc(tupdesc);
 289
 290         /* pages */
 291         values[0] = Int32GetDatum(metadata->nPendingPages);
 292         isnull[0] = false;
 293
 294         /* tuples */
 295         values[1] = Int64GetDatum(metadata->nPendingHeapTuples);
 296         isnull[1] = false;
 297
 298         UnlockReleaseBuffer(metabuffer);
 299
 300         tuple = heap_form_tuple(tupdesc, values, isnull);
 301         PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
 302 }