SQLite

# define VdbeCoverageIf(v,x)
# define VdbeCoverageAlwaysTaken(v)
# define VdbeCoverageNeverTaken(v)
# define VDBE_OFFSET_LINENO(x) 0
#endif

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
void sqlite3VdbeScanStatus(Vdbe*, int, int, int, i64, const char*);
#else
# define sqlite3VdbeScanStatus(a,b,c,d,e)
#endif

#endif

};

/* A bitfield type for use inside of structures.  Always follow with :N where
** N is the number of bits.
*/
typedef unsigned bft;  /* Bit Field Type */

typedef struct ScanStatus ScanStatus;
struct ScanStatus {
  int addrExplain;                /* OP_Explain for loop */
  int addrLoop;                   /* Address of "loops" counter */
  int addrVisit;                  /* Address of "rows visited" counter */
  i64 nEst;                       /* Estimated rows per loop */
  char *zName;                    /* Name of table or index */
};

  SubProgram *pProgram;   /* Linked list of all sub-programs used by VM */
  int nOnceFlag;          /* Size of array aOnceFlag[] */
  u8 *aOnceFlag;          /* Flags for OP_Once */
  AuxData *pAuxData;      /* Linked list of auxdata allocations */
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
  i64 *anExec;            /* Number of times each op has been executed */
  int nScan;              /* Entries in aScan[] */
  ScanStatus *aScan;      /* Scan definitions for sqlite3_stmt_scanstatus() */
#endif
};

/*
** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */

  sqlite3_int64 *pnLoop,          /* OUT: Number of times loop was run */
  sqlite3_int64 *pnVisit,         /* OUT: Number of rows visited (all loops) */
  sqlite3_int64 *pnEst,           /* OUT: Number of rows estimated (per loop) */
  const char **pzName,            /* OUT: Object name (table or index) */
  const char **pzExplain          /* OUT: EQP string */
){
  Vdbe *p = (Vdbe*)pStmt;
  ScanStatus *pScan;
  if( idx<0 || idx>=p->nScan ) return 1;
  pScan = &p->aScan[idx];
  if( pnLoop ) *pnLoop = p->anExec[pScan->addrLoop];
  if( pnVisit ) *pnVisit = p->anExec[pScan->addrVisit];
  if( pnEst ) *pnEst = pScan->nEst;
  if( *pzName ) *pzName = pScan->zName;
  if( *pzExplain ){

  return addr;
}

#if defined(SQLITE_ENABLE_STMT_SCANSTATUS)
/*
** Add an entry to the array of counters managed by sqlite3_stmt_scanstatus().
*/
void sqlite3VdbeScanStatus(
  Vdbe *p,                        /* VM to add scanstatus() to */
  int addrExplain,                /* Address of OP_Explain (or 0) */
  int addrLoop,                   /* Address of loop counter */ 
  int addrVisit,                  /* Address of rows visited counter */
  i64 nEst,                       /* Estimated number of rows */
  const char *zName               /* Name of table or index being scanned */
){
  int nByte = (p->nScan+1) * sizeof(ScanStatus);
  ScanStatus *aNew;
  aNew = (ScanStatus*)sqlite3DbRealloc(p->db, p->aScan, nByte);
  if( aNew ){
    ScanStatus *pNew = &aNew[p->nScan++];
    pNew->addrExplain = addrExplain;
    pNew->addrLoop = addrLoop;
    pNew->addrVisit = addrVisit;
    pNew->nEst = nEst;
    pNew->zName = sqlite3DbStrDup(p->db, zName);
    p->aScan = aNew;
  }

    explainAppendTerm(pStr, i, z, "<");
  }
  sqlite3StrAccumAppend(pStr, ")", 1);
}

/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command, or if either SQLITE_DEBUG or SQLITE_ENABLE_STMT_SCANSTATUS was
** defined at compile-time. If it is not a no-op, a single OP_Explain opcode 
** is added to the output to describe the table scan strategy in pLevel.
**
** If an OP_Explain opcode is added to the VM, its address is returned.
** Otherwise, if no OP_Explain is coded, zero is returned.
*/
static int explainOneScan(
  Parse *pParse,                  /* Parse context */
  SrcList *pTabList,              /* Table list this loop refers to */
  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
  int iLevel,                     /* Value for "level" column of output */
  int iFrom,                      /* Value for "from" column of output */

  return ret;
}
#else
# define explainOneScan(u,v,w,x,y,z) 0
#endif /* SQLITE_OMIT_EXPLAIN */

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
/*
** Configure the VM passed as the first argument with an
** sqlite3_stmt_scanstatus() entry corresponding to the scan used to 
** implement level pLvl. Argument pSrclist is a pointer to the FROM 
** clause that the scan reads data from.
**
** If argument addrExplain is not 0, it must be the address of an 
** OP_Explain instruction that describes the same loop.
*/
static void addScanStatus(
  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
  int addrExplain                 /* Address of OP_Explain (or 0) */
){
  const char *zObj = 0;
  i64 nEst = 1;
  WhereLoop *pLoop = pLvl->pWLoop;
  if( (pLoop->wsFlags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
    zObj = pLoop->u.btree.pIndex->zName;
  }else{
    zObj = pSrclist->a[pLvl->iFrom].zName;
  }
  if( pLoop->nOut>=10 ){
    nEst = sqlite3LogEstToInt(pLoop->nOut);
  }
  sqlite3VdbeScanStatus(
      v, addrExplain, pLvl->addrBody, pLvl->addrVisit, nEst, zObj
  );
}
#else
# define addScanStatus(a, b, c, d)
#endif

  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
  u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
  u8 eDistinct;             /* One of the WHERE_DISTINCT_* values below */
  u8 nLevel;                /* Number of nested loop */
  int iTop;                 /* The very beginning of the WHERE loop */
  int iContinue;            /* Jump here to continue with next record */
  int iBreak;               /* Jump here to break out of the loop */

  int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */
  int aiCurOnePass[2];      /* OP_OpenWrite cursors for the ONEPASS opt */
  WhereMaskSet sMaskSet;    /* Map cursor numbers to bitmasks */
  WhereClause sWC;          /* Decomposition of the WHERE clause */
  WhereLevel a[1];          /* Information about each nest loop in WHERE */
};

do_execsql_test 3.4.1 {
  SELECT count(*) FROM a1 WHERE rowid IN (1, 5, 10, 15);
} {4}
do_scanstatus_test 3.4.2 {
  nLoop 1 nVisit 4 nEst 4 zName a1
  zExplain {SEARCH TABLE a1 USING INTEGER PRIMARY KEY (rowid=?)}
}

#-------------------------------------------------------------------------
# Test that scanstatus() data is not available for searches performed
# by triggers.
#
# It is available for searches performed as part of FK processing, but 
# not FK action processing.
#
do_execsql_test 4.0 {
  CREATE TABLE t1(a, b, c);
  CREATE TABLE t2(x PRIMARY KEY, y, z);
  CREATE TRIGGER tr1 AFTER INSERT ON t1 BEGIN
    SELECT * FROM t2 WHERE x BETWEEN 20 AND 40;
  END;
  WITH d(x) AS (SELECT 1 UNION ALL SELECT x+1 AS n FROM d WHERE n<=100)
  INSERT INTO t2 SELECT x, x*2, x*3 FROM d;
}

do_execsql_test    4.1.1 { INSERT INTO t1 VALUES(1, 2, 3); }
do_scanstatus_test 4.1.2 { }

do_execsql_test 4.2 {
  CREATE TABLE p1(x PRIMARY KEY);
  INSERT INTO p1 VALUES(1), (2), (3), (4);
  CREATE TABLE c1(y REFERENCES p1);
  INSERT INTO c1 VALUES(1), (2), (3);
  PRAGMA foreign_keys=on;
}
do_execsql_test    4.2.1 { DELETE FROM p1 WHERE x=4 }
do_scanstatus_test 4.2.2 { 
  nLoop 1 nVisit 1 nEst 1 zName sqlite_autoindex_p1_1 
  zExplain {SEARCH TABLE p1 USING INDEX sqlite_autoindex_p1_1 (x=?)}

  nLoop 1 nVisit 3 nEst 524288 zName c1 zExplain {SCAN TABLE c1}
}

finish_test