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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

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Overview
Comment:More performance optimization for the LIKE and GLOB operators.
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Files: files | file ages | folders
SHA1: 5ab1023d6cfe31fa8a194804b8216058977ac973
User & Date: drh 2014-09-25 03:51:37
Context
2014-09-25
11:08
Still more performance enhancements to the LIKE and GLOB operators. check-in: 6c8924ca user: drh tags: trunk
03:51
More performance optimization for the LIKE and GLOB operators. check-in: 5ab1023d user: drh tags: trunk
02:44
Change that might allow SQLite to build and work using the EBCDIC character set. check-in: ef30e035 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/func.c.

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/*
** For LIKE and GLOB matching on EBCDIC machines, assume that every
** character is exactly one byte in size.  Also, all characters are
** able to participate in upper-case-to-lower-case mappings in EBCDIC
** whereas only characters less than 0x80 do in ASCII.
*/
#if defined(SQLITE_EBCDIC)
# define sqlite3Utf8Read(A)    (*((*A)++))
# define GlobUpperToLower(A)   A = sqlite3UpperToLower[A]

#else
# define GlobUpperToLower(A)   if( !((A)&~0x7f) ){ A = sqlite3UpperToLower[A]; }

#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };
/* The correct SQL-92 behavior is for the LIKE operator to ignore
** case.  Thus  'a' LIKE 'A' would be true. */
static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
................................................................................
  const u8 *zString,               /* The string to compare against the glob */
  const struct compareInfo *pInfo, /* Information about how to do the compare */
  u32 esc                          /* The escape character */
){
  u32 c, c2;
  int invert;
  int seen;
  u8 matchOne = pInfo->matchOne;
  u8 matchAll = pInfo->matchAll;
  u8 matchSet = pInfo->matchSet;
  u8 noCase = pInfo->noCase; 








  while( (c = sqlite3Utf8Read(&zPattern))!=0 ){
    if( c==matchAll ){
      while( (c=sqlite3Utf8Read(&zPattern)) == matchAll
               || c == matchOne ){
        if( c==matchOne && sqlite3Utf8Read(&zString)==0 ){
          return 0;
        }
      }
      if( c==0 ){
        return 1;
      }else if( c==esc ){

        c = sqlite3Utf8Read(&zPattern);
        if( c==0 ){
          return 0;
        }
      }else if( c==matchSet ){
        assert( esc==0 );         /* This is GLOB, not LIKE */
        assert( matchSet<0x80 );  /* '[' is a single-byte character */

        while( *zString && patternCompare(&zPattern[-1],zString,pInfo,esc)==0 ){
          SQLITE_SKIP_UTF8(zString);
        }
        return *zString!=0;
      }

      while( (c2 = sqlite3Utf8Read(&zString))!=0 ){
        if( noCase ){
          GlobUpperToLower(c2);
          GlobUpperToLower(c);
          while( c2 != 0 && c2 != c ){
            c2 = sqlite3Utf8Read(&zString);
            GlobUpperToLower(c2);
          }
        }else{
          while( c2 != 0 && c2 != c ){
            c2 = sqlite3Utf8Read(&zString);
          }
        }
        if( c2==0 ) return 0;
        if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;
      }
      return 0;

    }else if( c==matchOne ){
      if( sqlite3Utf8Read(&zString)==0 ){
        return 0;


      }

    }else if( c==matchSet ){




      u32 prior_c = 0;
      assert( esc==0 );    /* This only occurs for GLOB, not LIKE */
      seen = 0;
      invert = 0;
      c = sqlite3Utf8Read(&zString);
      if( c==0 ) return 0;
      c2 = sqlite3Utf8Read(&zPattern);
      if( c2=='^' ){
        invert = 1;
        c2 = sqlite3Utf8Read(&zPattern);
      }
      if( c2==']' ){
        if( c==']' ) seen = 1;
        c2 = sqlite3Utf8Read(&zPattern);
      }
      while( c2 && c2!=']' ){
        if( c2=='-' && zPattern[0]!=']' && zPattern[0]!=0 && prior_c>0 ){
          c2 = sqlite3Utf8Read(&zPattern);
          if( c>=prior_c && c<=c2 ) seen = 1;
          prior_c = 0;
        }else{
          if( c==c2 ){
            seen = 1;
          }
          prior_c = c2;
        }
        c2 = sqlite3Utf8Read(&zPattern);
      }
      if( c2==0 || (seen ^ invert)==0 ){
        return 0;
      }
    }else{



      c2 = sqlite3Utf8Read(&zString);
      if( c==esc ){
        c = sqlite3Utf8Read(&zPattern);
      }
      if( noCase ){
        GlobUpperToLower(c);
        GlobUpperToLower(c2);
      }
      if( c!=c2 ){
        return 0;
      }
    }
  }
  return *zString==0;
}

/*
** The sqlite3_strglob() interface.
*/







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/*
** For LIKE and GLOB matching on EBCDIC machines, assume that every
** character is exactly one byte in size.  Also, all characters are
** able to participate in upper-case-to-lower-case mappings in EBCDIC
** whereas only characters less than 0x80 do in ASCII.
*/
#if defined(SQLITE_EBCDIC)
# define sqlite3Utf8Read(A)        (*((*A)++))
# define GlobUpperToLower(A)       A = sqlite3UpperToLower[A]
# define GlobUpperToLowerAscii(A)  A = sqlite3UpperToLower[A]
#else
# define GlobUpperToLower(A)       if( A<=0x7f ){ A = sqlite3UpperToLower[A]; }
# define GlobUpperToLowerAscii(A)  A = sqlite3UpperToLower[A]
#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };
/* The correct SQL-92 behavior is for the LIKE operator to ignore
** case.  Thus  'a' LIKE 'A' would be true. */
static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
................................................................................
  const u8 *zString,               /* The string to compare against the glob */
  const struct compareInfo *pInfo, /* Information about how to do the compare */
  u32 esc                          /* The escape character */
){
  u32 c, c2;
  int invert;
  int seen;
  u32 matchOne = pInfo->matchOne;
  u32 matchAll = pInfo->matchAll;
  u32 matchOther;
  u8 noCase = pInfo->noCase;
  
  /* The GLOB operator does not have an ESCAPE clause.  And LIKE does not
  ** have the matchSet operator.  So we either have to look for one or
  ** the other, never both.  Hence the single variable matchOther is used
  ** to store the one we have to look for.
  */
  matchOther = esc ? esc : pInfo->matchSet;

  while( (c = sqlite3Utf8Read(&zPattern))!=0 ){
    if( c==matchAll ){
      while( (c=sqlite3Utf8Read(&zPattern)) == matchAll
               || c == matchOne ){
        if( c==matchOne && sqlite3Utf8Read(&zString)==0 ){
          return 0;
        }
      }
      if( c==0 ){
        return 1;
      }else if( c==matchOther ){
        if( esc ){
          c = sqlite3Utf8Read(&zPattern);
          if( c==0 ) return 0;

        }else{


          assert( matchOther<0x80 );  /* '[' is a single-byte character */
          while( *zString
                 && patternCompare(&zPattern[-1],zString,pInfo,esc)==0 ){
            SQLITE_SKIP_UTF8(zString);
          }
          return *zString!=0;
        }
      }
      while( (c2 = sqlite3Utf8Read(&zString))!=0 ){
        if( noCase && c<0x80 ){
          GlobUpperToLower(c2);
          GlobUpperToLowerAscii(c);
          while( c2 != 0 && c2 != c ){
            do{ c2 = *(zString++); }while( c2>0x7f );
            GlobUpperToLowerAscii(c2);
          }
        }else{
          while( c2 != 0 && c2 != c ){
            c2 = sqlite3Utf8Read(&zString);
          }
        }
        if( c2==0 ) return 0;
        if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;
      }
      return 0;
    }
    if( c==matchOne ){
      if( sqlite3Utf8Read(&zString)==0 ){
        return 0;
      }else{
        continue;
      }
    }
    if( c==matchOther ){
      if( esc ){
        c = sqlite3Utf8Read(&zPattern);
        if( c==0 ) return 0;
      }else{
        u32 prior_c = 0;

        seen = 0;
        invert = 0;
        c = sqlite3Utf8Read(&zString);
        if( c==0 ) return 0;
        c2 = sqlite3Utf8Read(&zPattern);
        if( c2=='^' ){
          invert = 1;
          c2 = sqlite3Utf8Read(&zPattern);
        }
        if( c2==']' ){
          if( c==']' ) seen = 1;
          c2 = sqlite3Utf8Read(&zPattern);
        }
        while( c2 && c2!=']' ){
          if( c2=='-' && zPattern[0]!=']' && zPattern[0]!=0 && prior_c>0 ){
            c2 = sqlite3Utf8Read(&zPattern);
            if( c>=prior_c && c<=c2 ) seen = 1;
            prior_c = 0;
          }else{
            if( c==c2 ){
              seen = 1;
            }
            prior_c = c2;
          }
          c2 = sqlite3Utf8Read(&zPattern);
        }
        if( c2==0 || (seen ^ invert)==0 ){
          return 0;
        }

        continue;
      }
    }
    c2 = sqlite3Utf8Read(&zString);
    if( c==c2 ) continue;


    if( !noCase ) return 0;
    GlobUpperToLower(c);
    GlobUpperToLower(c2);

    if( c!=c2 ) return 0;



  }
  return *zString==0;
}

/*
** The sqlite3_strglob() interface.
*/