63 lines
2.3 KiB
Groff
63 lines
2.3 KiB
Groff
.Dd March 11, 2017
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.Dt SQLITE_SCANSTAT_NLOOP 3
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.Os
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.Sh NAME
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.Nm SQLITE_SCANSTAT_NLOOP ,
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.Nm SQLITE_SCANSTAT_NVISIT ,
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.Nm SQLITE_SCANSTAT_EST ,
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.Nm SQLITE_SCANSTAT_NAME ,
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.Nm SQLITE_SCANSTAT_EXPLAIN ,
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.Nm SQLITE_SCANSTAT_SELECTID
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.Nd Prepared Statement Scan Status Opcodes
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.Sh SYNOPSIS
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.Fd #define SQLITE_SCANSTAT_NLOOP
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.Fd #define SQLITE_SCANSTAT_NVISIT
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.Fd #define SQLITE_SCANSTAT_EST
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.Fd #define SQLITE_SCANSTAT_NAME
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.Fd #define SQLITE_SCANSTAT_EXPLAIN
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.Fd #define SQLITE_SCANSTAT_SELECTID
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.Sh DESCRIPTION
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The following constants can be used for the T parameter to the sqlite3_stmt_scanstatus(S,X,T,V)
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interface.
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Each constant designates a different metric for sqlite3_stmt_scanstatus()
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to return.
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.Pp
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When the value returned to V is a string, space to hold that string
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is managed by the prepared statement S and will be automatically freed
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when S is finalized.
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.Bl -tag -width Ds
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.It SQLITE_SCANSTAT_NLOOP
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The sqlite3_int64 variable pointed to by the T parameter
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will be set to the total number of times that the X-th loop has run.
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.It SQLITE_SCANSTAT_NVISIT
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The sqlite3_int64 variable pointed to by the T parameter
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will be set to the total number of rows examined by all iterations
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of the X-th loop.
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.It SQLITE_SCANSTAT_EST
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The "double" variable pointed to by the T parameter will be set to
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the query planner's estimate for the average number of rows output
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from each iteration of the X-th loop.
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If the query planner's estimates was accurate, then this value will
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approximate the quotient NVISIT/NLOOP and the product of this value
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for all prior loops with the same SELECTID will be the NLOOP value
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for the current loop.
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.It SQLITE_SCANSTAT_NAME
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The "const char *" variable pointed to by the T parameter will be set
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to a zero-terminated UTF-8 string containing the name of the index
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or table used for the X-th loop.
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.It SQLITE_SCANSTAT_EXPLAIN
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The "const char *" variable pointed to by the T parameter will be set
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to a zero-terminated UTF-8 string containing the EXPLAIN QUERY PLAN
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description for the X-th loop.
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.It SQLITE_SCANSTAT_SELECT
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The "int" variable pointed to by the T parameter will be set to the
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"select-id" for the X-th loop.
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The select-id identifies which query or subquery the loop is part of.
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The main query has a select-id of zero.
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The select-id is the same value as is output in the first column of
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an EXPLAIN QUERY PLAN query.
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.El
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.Pp
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.Sh SEE ALSO
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.Xr sqlite_int64 3
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