tool/index_usage.c

   1 /*
   2 ** 2018-12-04
   3 **
   4 ** The author disclaims copyright to this source code.  In place of
   5 ** a legal notice, here is a blessing:
   6 **
   7 **    May you do good and not evil.
   8 **    May you find forgiveness for yourself and forgive others.
   9 **    May you share freely, never taking more than you give.
  10 **
  11 *************************************************************************
  12 **
  13 ** This file implements a utility program used to help determine which
  14 ** indexes in a database schema are used and unused, and how often specific
  15 ** indexes are used.
  16 */
  17 #include "sqlite3.h"
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <assert.h>
  21 #include <string.h>
  22
  23 static void usage(const char *argv0){
  24   printf("Usage: %s [OPTIONS] DATABASE LOG\n\n", argv0);
  25   printf(
  26     "DATABASE is an SQLite database against which various statements\n"
  27     "have been run.  The SQL text is stored in LOG.  LOG is an SQLite\n"
  28     "database with this schema:\n"
  29     "\n"
  30     "    CREATE TABLE sqllog(sql TEXT);\n"
  31     "\n"
  32     "This utility program analyzes statements contained in LOG and prints\n"
  33     "a report showing how many times each index in DATABASE is used by the\n"
  34     "statements in LOG.\n"
  35     "\n"
  36     "DATABASE only needs to contain the schema used by the statements in\n"
  37     "LOG. The content can be removed from DATABASE.\n"
  38   );
  39   printf(
  40     "\nOPTIONS:\n\n"
  41     "    --progress N   Show a progress message after every N input rows\n"
  42     "    -q             Omit error message when parsing log entries\n"
  43     "    --using NAME   Print SQL statements that use index NAME\n"
  44   );
  45   printf("\nAnalysis will be done by SQLite version %s dated %.20s\n"
  46          "checkin number %.40s. Different versions\n"
  47          "of SQLite might use different indexes.\n",
  48          sqlite3_libversion(), sqlite3_sourceid(), sqlite3_sourceid()+21);
  49   exit(1);
  50 }
  51
  52 int main(int argc, char **argv){
  53   sqlite3 *db = 0;          /* The main database */
  54   sqlite3_stmt *pStmt = 0;  /* a query */
  55   char *zSql;
  56   int nErr = 0;
  57   int rc;
  58   int bQuiet = 0;
  59   int i, j;
  60   const char *zUsing = 0;
  61   sqlite3_stmt *pIncrCnt = 0;
  62   int nRow = 0;
  63   int iProgress = 0;
  64
  65   for(i=j=1; i<argc; i++){
  66     const char *z = argv[i];
  67     if( z[0]=='-' ){
  68       z++;
  69       if( z[0]=='-' ) z++;
  70       if( strcmp(z,"progress")==0 ){
  71         if( i+1<argc ){
  72           iProgress = strtol(argv[++i],0,0);
  73           continue;
  74         }
  75         printf("The --progress option requires an argument\n");
  76         exit(0);
  77       }
  78       if( strcmp(z,"q")==0 ){
  79         bQuiet = 1;
  80         continue;
  81       }
  82       if( strcmp(z,"using")==0 ){
  83         if( i+1<argc ){
  84           zUsing = argv[++i];
  85           continue;
  86         }
  87         printf("The --using option requires an argument\n");
  88         exit(0);
  89       }
  90       if( strcmp(z, "help")==0 || strcmp(z, "?")==0 ){
  91         usage(argv[0]);
  92       }
  93       printf("Unknown command-line option: \"%s\"\n", argv[i]);
  94       exit(0);
  95     }else{
  96       if( j<i ) argv[j++] = argv[i];
  97     }
  98   }
  99   argc = j;
 100
 101   if( argc!=3 ) usage(argv[0]);
 102   rc = sqlite3_open_v2(argv[1], &db, SQLITE_OPEN_READONLY, 0);
 103   if( rc ){
 104     printf("Cannot open \"%s\" for reading: %s\n", argv[1], sqlite3_errmsg(db));
 105     goto errorOut;
 106   }
 107   rc = sqlite3_prepare_v2(db, "SELECT * FROM sqlite_schema", -1, &pStmt, 0);
 108   if( rc ){
 109     printf("Cannot read the schema from \"%s\" - %s\n", argv[1],
 110            sqlite3_errmsg(db));
 111     goto errorOut;
 112   }
 113   sqlite3_finalize(pStmt);
 114   pStmt = 0;
 115   rc = sqlite3_exec(db,
 116      "CREATE TABLE temp.idxu(\n"
 117      "  tbl TEXT COLLATE nocase,\n"
 118      "  idx TEXT COLLATE nocase,\n"
 119      "  cnt INT,\n"
 120      "  PRIMARY KEY(idx)\n"
 121      ") WITHOUT ROWID;", 0, 0, 0);
 122   if( rc ){
 123     printf("Cannot create the result table - %s\n",
 124            sqlite3_errmsg(db));
 125     goto errorOut;
 126   }
 127   rc = sqlite3_exec(db,
 128      "INSERT INTO temp.idxu(tbl,idx,cnt)"
 129      " SELECT tbl_name, name, 0 FROM sqlite_schema"
 130      " WHERE type='index' AND sql IS NOT NULL", 0, 0, 0);
 131
 132   /* Open the LOG database */
 133   zSql = sqlite3_mprintf("ATTACH %Q AS log", argv[2]);
 134   rc = sqlite3_exec(db, zSql, 0, 0, 0);
 135   sqlite3_free(zSql);
 136   if( rc ){
 137     printf("Cannot open the LOG database \"%s\" - %s\n",
 138            argv[2], sqlite3_errmsg(db));
 139     goto errorOut;
 140   }
 141   rc = sqlite3_prepare_v2(db,
 142      "SELECT sql, rowid FROM log.sqllog"
 143      " WHERE upper(substr(sql,1,5)) NOT IN ('BEGIN','COMMI','ROLLB','PRAGM')",
 144                           -1, &pStmt, 0);
 145   if( rc ){
 146     printf("Cannot read the SQLLOG table in the LOG database \"%s\" - %s\n",
 147            argv[2], sqlite3_errmsg(db));
 148     goto errorOut;
 149   }
 150
 151   rc = sqlite3_prepare_v2(db,
 152     "UPDATE temp.idxu SET cnt=cnt+1 WHERE idx=?1",
 153     -1, &pIncrCnt, 0);
 154   if( rc ){
 155     printf("Cannot prepare a statement to increment a counter for "
 156            "indexes used\n");
 157     goto errorOut;
 158   }
 159
 160   /* Update the counts based on LOG */
 161   while( sqlite3_step(pStmt)==SQLITE_ROW ){
 162     const char *zLog = (const char*)sqlite3_column_text(pStmt, 0);
 163     sqlite3_stmt *pS2;
 164     if( zLog==0 ) continue;
 165     zSql = sqlite3_mprintf("EXPLAIN QUERY PLAN %s", zLog);
 166     rc = sqlite3_prepare_v2(db, zSql, -1, &pS2, 0);
 167     sqlite3_free(zSql);
 168     if( rc ){
 169       if( !bQuiet ){
 170         printf("Cannot compile LOG entry %d (%s): %s\n",
 171              sqlite3_column_int(pStmt, 1), zLog, sqlite3_errmsg(db));
 172         fflush(stdout);
 173       }
 174       nErr++;
 175     }else{
 176       nRow++;
 177       if( iProgress>0 && (nRow%iProgress)==0 ){
 178         printf("%d...\n", nRow);
 179         fflush(stdout);
 180       }
 181       while( sqlite3_step(pS2)==SQLITE_ROW ){
 182         const char *zExplain = (const char*)sqlite3_column_text(pS2,3);
 183         const char *z1, *z2;
 184         int n;
 185         /* printf("EXPLAIN: %s\n", zExplain); */
 186         z1 = strstr(zExplain, " USING INDEX ");
 187         if( z1==0 ) continue;
 188         z1 += 13;
 189         for(z2=z1+1; z2[0] && z2[1]!='('; z2++){}
 190         n = z2 - z1;
 191         if( zUsing && sqlite3_strnicmp(zUsing, z1, n)==0 ){
 192           printf("Using %s:\n%s\n", zUsing, zLog);
 193           fflush(stdout);
 194         }
 195         sqlite3_bind_text(pIncrCnt,1,z1,n,SQLITE_STATIC);
 196         sqlite3_step(pIncrCnt);
 197         sqlite3_reset(pIncrCnt);
 198       }
 199     }
 200     sqlite3_finalize(pS2);
 201   }
 202   sqlite3_finalize(pStmt);
 203
 204   /* Generate the report */
 205   rc = sqlite3_prepare_v2(db,
 206      "SELECT tbl, idx, cnt, "
 207      "   (SELECT group_concat(name,',') FROM pragma_index_info(idx))"
 208      " FROM temp.idxu, main.sqlite_schema"
 209      " WHERE temp.idxu.tbl=main.sqlite_schema.tbl_name"
 210      "   AND temp.idxu.idx=main.sqlite_schema.name"
 211      " ORDER BY cnt DESC, tbl, idx",
 212      -1, &pStmt, 0);
 213   if( rc ){
 214     printf("Cannot query the result table - %s\n",
 215            sqlite3_errmsg(db));
 216     goto errorOut;
 217   }
 218   while( sqlite3_step(pStmt)==SQLITE_ROW ){
 219     printf("%10d %s on %s(%s)\n",
 220        sqlite3_column_int(pStmt, 2),
 221        sqlite3_column_text(pStmt, 1),
 222        sqlite3_column_text(pStmt, 0),
 223        sqlite3_column_text(pStmt, 3));
 224   }
 225   sqlite3_finalize(pStmt);
 226   pStmt = 0;
 227
 228 errorOut:
 229   sqlite3_finalize(pIncrCnt);
 230   sqlite3_finalize(pStmt);
 231   sqlite3_close(db);
 232   return nErr;
 233 }