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## SQLite C Interface

## Prepared Statement Scan Status Opcodes

>     #define SQLITE_SCANSTAT_NLOOP    0
>     #define SQLITE_SCANSTAT_NVISIT   1
>     #define SQLITE_SCANSTAT_EST      2
>     #define SQLITE_SCANSTAT_NAME     3
>     #define SQLITE_SCANSTAT_EXPLAIN  4
>     #define SQLITE_SCANSTAT_SELECTID 5

The following constants can be used for the T parameter to the sqlite3_stmt_scanstatus(S,X,T,V) interface. Each constant designates a different metric for sqlite3_stmt_scanstatus() to return.

When the value returned to V is a string, space to hold that string is managed by the prepared statement S and will be automatically freed when S is finalized.

SQLITE_SCANSTAT_NLOOP
  The sqlite3_int64 variable pointed to by the T parameter will be set to the total number of times that the X-th loop has run.

SQLITE_SCANSTAT_NVISIT
  The sqlite3_int64 variable pointed to by the T parameter will be set to the total number of rows examined by all iterations of the X-th loop.

SQLITE_SCANSTAT_EST
  The "double" variable pointed to by the T parameter will be set to the query planner's estimate for the average number of rows output from each iteration of the X-th loop. If the query planner's estimates was accurate, then this value will approximate the quotient NVISIT/NLOOP and the product of this value for all prior loops with the same SELECTID will be the NLOOP value for the current loop.

SQLITE_SCANSTAT_NAME
  The "const char *" variable pointed to by the T parameter will be set to a zero-terminated UTF-8 string containing the name of the index or table used for the X-th loop.

SQLITE_SCANSTAT_EXPLAIN
  The "const char *" variable pointed to by the T parameter will be set to a zero-terminated UTF-8 string containing the EXPLAIN QUERY PLAN description for the X-th loop.

SQLITE_SCANSTAT_SELECT
  The "int" variable pointed to by the T parameter will be set to the "select-id" for the X-th loop. The select-id identifies which query or subquery the loop is part of. The main query has a select-id of zero. The select-id is the same value as is output in the first column of an EXPLAIN QUERY PLAN query.

See also lists of Objects, Constants, and Functions.