> If I use prepared statement like this "update table set field1=?, field2=?
> where field3=?" for performance reasons, is there a way to update only
> some fields and leave other untouched without overhead of building
> separate queries on the fly or selecting old values with different query?

If you are using UPDATE, then is it not reasonable to expect that you would know what the original values for of each field?

So, it should not be difficult to provide same in the UPDATE statement.

If not, what is the "real cost" (time) of preparing statement?


<showing my ignorance of API>
Must a statement with parameters be prepared before it can be executed via the client?
</showing my ignorance of API>

Cus, it seems that what you are asking the engine to maintain a cache of previously executed statements.

So if you execute any un-prepared statements, the engine would compare the SQL text against the cache list and re-use the previously prepared version, instead of preparing the statement a new -- thus bypassing the "prepare" stage.


Is that the real issue, you want to eliminate the "prepare" stage?


Sean