Is there a limit to SQL statement size?
Yes. Applications using Firebird 3.0 API and above have the limit of 10MB. The engine itself can support up to 4GB, but the size is limited to 10MB as a precaution.
Earlier versions of Firebird API have a limit of 64kB (65536 characters in a single-byte character set). Also, the BLR that comes out as a result must also fit into 64kB. If you don't know what BLR is, read FAQ #187. Additionally, the query plan has to fit in 48kB.