Thread: pgsql: Fix hypothetical bug in ExprState building for hashing
Fix hypothetical bug in ExprState building for hashing adf97c156 gave ExprStates the ability to hash expressions and return a single hash value. That commit supports seeding the hash value with an initial value to have that blended into the final hash value. Here we fix a hypothetical bug where if there are zero expressions to hash, the initial value is stored in the wrong location. The existing code stored the initial value in an intermediate location expecting that when the expressions were hashed that those steps would store the final hash value in the ExprState.resvalue field. However, that wouldn't happen when there are zero expressions to hash. The correct thing to do instead is to have a special case for zero expressions and when we hit that case, store the initial value directly in the ExprState.resvalue. The reason that this is a hypothetical bug is that no code currently calls ExecBuildHash32Expr passing a non-zero initial value. Discussion: https://postgr.es/m/CAApHDvpMAL_zxbMRr1LOex3O7Y7R7ZN2i8iUFLQhqQiJMAg3qw@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/87f81a55632107006e5006a2d0bc5272ebaeca64 Modified Files -------------- src/backend/executor/execExpr.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-)