SQLite

**
*************************************************************************
*/

#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1

/*
** Stuff that is available inside the amalgamation, but which we need to
** declare ourselves if this module is compiled separately.
*/
#ifndef SQLITE_AMALGAMATION
# include <string.h>
# include <stdio.h>
# include <stdlib.h>
# include <assert.h>


typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
#define get4byte(x) (        \
    ((u32)((x)[0])<<24) +    \
    ((u32)((x)[1])<<16) +    \
    ((u32)((x)[2])<<8) +     \
    ((u32)((x)[3]))          \
)
#endif

typedef struct CidxTable CidxTable;
typedef struct CidxCursor CidxCursor;

struct CidxTable {
  sqlite3_vtab base;              /* Base class.  Must be first */
  sqlite3 *db;
};

struct CidxCursor {
  sqlite3_vtab_cursor base;       /* Base class.  Must be first */
  sqlite3_int64 iRowid;           /* Row number of the output */
  char *zIdxName;                 /* Copy of the index_name parameter */
  char *zAfterKey;                /* Copy of the after_key parameter */
  sqlite3_stmt *pStmt;            /* SQL statement that generates the output */
};

typedef struct CidxColumn CidxColumn;
struct CidxColumn {
  char *zExpr;                    /* Text for indexed expression */
  int bDesc;                      /* True for DESC columns, otherwise false */
  int bKey;                       /* Part of index, not PK */

  va_start(ap, zFmt);
  assert( pCsr->base.pVtab->zErrMsg==0 );
  pCsr->base.pVtab->zErrMsg = sqlite3_vmprintf(zFmt, ap);
  va_end(ap);
}

/*
** Connect to the incremental_index_check virtual table.
*/
static int cidxConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  int rc = SQLITE_OK;
  CidxTable *pRet;

#define IIC_ERRMSG        0
#define IIC_CURRENT_KEY   1
#define IIC_INDEX_NAME    2
#define IIC_AFTER_KEY     3
#define IIC_SCANNER_SQL   4
  rc = sqlite3_declare_vtab(db,
      "CREATE TABLE xyz("
      " errmsg TEXT,"            /* Error message or NULL if everything is ok */
      " current_key TEXT,"       /* SQLite quote() text of key values */
      " index_name HIDDEN,"      /* IN: name of the index being scanned */
      " after_key HIDDEN,"       /* IN: Start scanning after this key */
      " scanner_sql HIDDEN"      /* debuggingn info: SQL used for scanner */
      ")"
  );
  pRet = cidxMalloc(&rc, sizeof(CidxTable));
  if( pRet ){
    pRet->db = db;
  }

static int cidxDisconnect(sqlite3_vtab *pVtab){
  CidxTable *pTab = (CidxTable*)pVtab;
  sqlite3_free(pTab);
  return SQLITE_OK;
}

/*
** idxNum and idxStr are not used.  There are only three possible plans,
** which are all distinguished by the number of parameters.
**
**   No parameters:         A degenerate plan.  The result is zero rows.
**   1 Parameter:           Scan all of the index starting with first entry
**   2 parameters:          Scan the index starting after the "after_key".    
**
** Provide successively smaller costs for each of these plans to encourage
** the query planner to select the one with the most parameters.
*/
static int cidxBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pInfo){
  int iIdxName = -1;
  int iAfterKey = -1;
  int i;

  for(i=0; i<pInfo->nConstraint; i++){

/*
** Close a btreeinfo cursor.
*/
static int cidxClose(sqlite3_vtab_cursor *pCursor){
  CidxCursor *pCsr = (CidxCursor*)pCursor;
  sqlite3_finalize(pCsr->pStmt);
  sqlite3_free(pCsr->zIdxName);
  sqlite3_free(pCsr->zAfterKey);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** Move a btreeinfo cursor to the next entry in the file.
*/

          break;
      }
    }
  }

  return zRet;
}

/*
** Generate SQL (in memory obtained from sqlite3_malloc()) that will
** continue the index scan for zIdxName starting after zAfterKey.
*/
int cidxGenerateScanSql(
  CidxCursor *pCsr,           /* The cursor which needs the new statement */
  const char *zIdxName,       /* index to be scanned */
  const char *zAfterKey,      /* start after this key, if not NULL */
  char **pzSqlOut             /* OUT: Write the generated SQL here */
){
  int rc;
  char *zTab = 0;
  char *zCurrentKey = 0;
  char *zOrderBy = 0;
  char *zSubWhere = 0;
  char *zSubExpr = 0;
  char *zSrcList = 0;
  char **azAfter = 0;
  CidxIndex *pIdx = 0;

  *pzSqlOut = 0;
  rc = cidxLookupIndex(pCsr, zIdxName, &pIdx, &zTab);

  zOrderBy = cidxColumnList(&rc, zIdxName, pIdx, CIDX_CLIST_ORDERBY);
  zCurrentKey = cidxColumnList(&rc, zIdxName, pIdx, CIDX_CLIST_CURRENT_KEY);
  zSubWhere = cidxColumnList(&rc, zIdxName, pIdx, CIDX_CLIST_SUBWHERE);
  zSubExpr = cidxColumnList(&rc, zIdxName, pIdx, CIDX_CLIST_SUBEXPR);
  zSrcList = cidxColumnList(&rc, zIdxName, pIdx, CIDX_CLIST_ALL);

  if( rc==SQLITE_OK && zAfterKey ){
    rc = cidxDecodeAfter(pCsr, pIdx->nCol, zAfterKey, &azAfter);
  }

  if( rc || zAfterKey==0 ){
    *pzSqlOut = cidxMprintf(&rc,
        "SELECT (SELECT %s FROM %Q AS t WHERE %s), %s "
        "FROM (SELECT %s FROM %Q ORDER BY %s) AS i",
        zSubExpr, zTab, zSubWhere, zCurrentKey, 
        zSrcList, zTab, zOrderBy
    );
  }else{
    const char *zSep = "";
    char *zSql;
    int i;

    zSql = cidxMprintf(&rc, 
        "SELECT (SELECT %s FROM %Q WHERE %s), %s FROM (",
        zSubExpr, zTab, zSubWhere, zCurrentKey
    );
    for(i=pIdx->nCol-1; i>=0; i--){
      int j;
      if( pIdx->aCol[i].bDesc && azAfter[i]==0 ) continue;
      for(j=0; j<2; j++){
        char *zWhere = cidxWhere(&rc, pIdx->aCol, azAfter, i, j);
        zSql = cidxMprintf(&rc, "%z"
            "%sSELECT * FROM (SELECT %s FROM %Q WHERE %z ORDER BY %s)",
            zSql, zSep, zSrcList, zTab, zWhere, zOrderBy
        );
        zSep = " UNION ALL ";
        if( pIdx->aCol[i].bDesc==0 ) break;
      }
    }
    *pzSqlOut = cidxMprintf(&rc, "%z) AS i", zSql);
  }

  sqlite3_free(zTab);
  sqlite3_free(zCurrentKey);
  sqlite3_free(zOrderBy);
  sqlite3_free(zSubWhere);
  sqlite3_free(zSubExpr);
  sqlite3_free(zSrcList);
  cidxFreeIndex(pIdx);
  sqlite3_free(azAfter);
  return rc;
}


/* 
** Position a cursor back to the beginning.
*/
static int cidxFilter(
  sqlite3_vtab_cursor *pCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  int rc = SQLITE_OK;
  CidxCursor *pCsr = (CidxCursor*)pCursor;
  const char *zIdxName = 0;
  const char *zAfterKey = 0;

  sqlite3_free(pCsr->zIdxName);
  pCsr->zIdxName = 0;
  sqlite3_free(pCsr->zAfterKey);
  pCsr->zAfterKey = 0;
  sqlite3_finalize(pCsr->pStmt);
  pCsr->pStmt = 0;

  if( argc>0 ){
    zIdxName = (const char*)sqlite3_value_text(argv[0]);
    if( argc>1 ){
      zAfterKey = (const char*)sqlite3_value_text(argv[1]);
    }
  }

  if( zIdxName ){



    char *zSql = 0;


    pCsr->zIdxName = sqlite3_mprintf("%s", zIdxName);


    pCsr->zAfterKey = zAfterKey ? sqlite3_mprintf("%s", zAfterKey) : 0;

    rc = cidxGenerateScanSql(pCsr, zIdxName, zAfterKey, &zSql);




















    if( zSql ){






















      pCsr->pStmt = cidxPrepare(&rc, pCsr, "%z", zSql);
    }









  }

  if( pCsr->pStmt ){
    assert( rc==SQLITE_OK );
    rc = cidxNext(pCursor);
  }
  pCsr->iRowid = 1;
  return rc;
}

/* 
** Return a column value.
*/
static int cidxColumn(
  sqlite3_vtab_cursor *pCursor, 
  sqlite3_context *ctx, 
  int iCol
){
  CidxCursor *pCsr = (CidxCursor*)pCursor;
  assert( iCol>=IIC_ERRMSG && iCol<=IIC_SCANNER_SQL );
  switch( iCol ){
    case IIC_ERRMSG: {
      const char *zVal = 0;
      if( sqlite3_column_type(pCsr->pStmt, 0)==SQLITE_INTEGER ){
        if( sqlite3_column_int(pCsr->pStmt, 0)==0 ){
          zVal = "row data mismatch";
        }
      }else{
        zVal = "row missing";
      }
      sqlite3_result_text(ctx, zVal, -1, SQLITE_STATIC);
      break;
    }
    case IIC_CURRENT_KEY: {
      sqlite3_result_value(ctx, sqlite3_column_value(pCsr->pStmt, 1));
      break;
    }
    case IIC_INDEX_NAME: {
      sqlite3_result_text(ctx, pCsr->zIdxName, -1, SQLITE_TRANSIENT);
      break;
    }
    case IIC_AFTER_KEY: {
      sqlite3_result_text(ctx, pCsr->zAfterKey, -1, SQLITE_TRANSIENT);
      break;
    }
    case IIC_SCANNER_SQL: {
      char *zSql = 0;
      cidxGenerateScanSql(pCsr, pCsr->zIdxName, pCsr->zAfterKey, &zSql);
      sqlite3_result_text(ctx, zSql, -1, sqlite3_free);
      break;
    }
  }
  return SQLITE_OK;
}

/* Return the ROWID for the sqlite_btreeinfo table */
static int cidxRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  CidxCursor *pCsr = (CidxCursor*)pCursor;
  *pRowid = pCsr->iRowid;
  return SQLITE_OK;
}

/*
** Register the virtual table modules with the database handle passed
** as the only argument.
*/

  uplevel [list do_test $tn.2 "incr_index_check $idx 1" [list {*}$res]]
  uplevel [list do_test $tn.3 "incr_index_check $idx 2" [list {*}$res]]
  uplevel [list do_test $tn.4 "incr_index_check $idx 5" [list {*}$res]]
}


do_execsql_test 1.2.1 {
  SELECT rowid, errmsg IS NULL, current_key FROM incremental_index_check('i1');
} {
  1 1 'five',5
  2 1 'four',4
  3 1 'one',1
  4 1 'three',3
  5 1 'two',2
}
do_execsql_test 1.2.2 {
  SELECT errmsg IS NULL, current_key, index_name, after_key, scanner_sql
    FROM incremental_index_check('i1') LIMIT 1;
} {
  1
  'five',5
  i1
  {}
  {SELECT (SELECT a IS i.i0 FROM 't1' AS t WHERE "rowid" COLLATE BINARY IS i.i1), quote(i0)||','||quote(i1) FROM (SELECT (a) AS i0, ("rowid" COLLATE BINARY) AS i1 FROM 't1' ORDER BY 1,2) AS i}
}

do_index_check_test 1.3 i1 {
  {} 'five',5
  {} 'four',4
  {} 'one',1
  {} 'three',3