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| author | drh <drh@noemail.net> | 2013-09-06 15:23:29 +0000 |
|---|---|---|
| committer | drh <drh@noemail.net> | 2013-09-06 15:23:29 +0000 |
| commit | cca9f3d291179e8126f29622f1a5c43105d1a045 (patch) | |
| tree | 1a42774e29913694f47f65b6fe916fb253b147e0 /src/func.c | |
| parent | d36e1041120280adfc9612d8f6e4ade318b3ffa0 (diff) | |
| download | sqlite-cca9f3d291179e8126f29622f1a5c43105d1a045.tar.gz sqlite-cca9f3d291179e8126f29622f1a5c43105d1a045.zip | |
Initial implementation of the unlikely() SQL function used as a hint to
the query planner.
FossilOrigin-Name: 036fc37a034093a4c6fc190633bd41c2b7230d77
Diffstat (limited to 'src/func.c')
| -rw-r--r-- | src/func.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/src/func.c b/src/func.c index 64e33640b..26cbfbfb0 100644 --- a/src/func.c +++ b/src/func.c @@ -418,14 +418,14 @@ static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){ } /* -** The COALESCE() and IFNULL() functions are implemented as VDBE code so -** that unused argument values do not have to be computed. However, we -** still need some kind of function implementation for this routines in -** the function table. That function implementation will never be called -** so it doesn't matter what the implementation is. We might as well use -** the "version()" function as a substitute. +** Some functions like COALESCE() and IFNULL() and UNLIKELY() are implemented +** as VDBE code so that unused argument values do not have to be computed. +** However, we still need some kind of function implementation for this +** routines in the function table. The noopFunc macro provides this. +** noopFunc will never be called so it doesn't matter what the implementation +** is. We might as well use the "version()" function as a substitute. */ -#define ifnullFunc versionFunc /* Substitute function - never called */ +#define noopFunc versionFunc /* Substitute function - never called */ /* ** Implementation of random(). Return a random integer. @@ -1659,9 +1659,11 @@ void sqlite3RegisterGlobalFunctions(void){ FUNCTION(lower, 1, 0, 0, lowerFunc ), FUNCTION(coalesce, 1, 0, 0, 0 ), FUNCTION(coalesce, 0, 0, 0, 0 ), - FUNCTION2(coalesce, -1, 0, 0, ifnullFunc, SQLITE_FUNC_COALESCE), + FUNCTION2(coalesce, -1, 0, 0, noopFunc, SQLITE_FUNC_COALESCE), FUNCTION(hex, 1, 0, 0, hexFunc ), - FUNCTION2(ifnull, 2, 0, 0, ifnullFunc, SQLITE_FUNC_COALESCE), + FUNCTION2(ifnull, 2, 0, 0, noopFunc, SQLITE_FUNC_COALESCE), + FUNCTION2(unlikely, 1, 0, 0, noopFunc, SQLITE_FUNC_UNLIKELY), + FUNCTION2(unlikely, 2, 0, 0, noopFunc, SQLITE_FUNC_UNLIKELY), FUNCTION(random, 0, 0, 0, randomFunc ), FUNCTION(randomblob, 1, 0, 0, randomBlob ), FUNCTION(nullif, 2, 0, 1, nullifFunc ), |