c++ - OCI Prefetch not working -

we have application using oci, cannot seem make prefetch working.

we have select query on table dozen of columns (amongst 1 clob column , 1 mdsys.geometry column). clob column in 99% of cases smaller 4000 bytes , in 50% of cases empty.

process follows:

• we set oci_attr_prefetch_rows 500
• we bind columns output buffers, clob bind directly text buffer of 8000 bytes
• for clob handle, set oci_attr_lobprefetch_size 8000
• we use ocistmtexecute iters 1 one row fetched buffer.

now if wireshark see network packets never filled (there 1 record per roundtrip).

if execute same select query sqldeveloper packets nicely filled, can assume row prefetching should work.

what missing here?

since ran same problem recently: oci_attr_prefetch_rows , oci_attr_lobprefetch_size don't work together.

from oracle docs:

prefetching not in effect if long, lob or opaque type columns (such xmltype) part of query.

whenever have lobs in result set, can't use implicit prefetching via oci_attr_prefetch_rows , instead need use explicit row-fetching calling ocistmtfetch2() rowcount > 1. of course need setup buffers in advance, keep track of consumed rows , need call ocidefinearrayofstruct() inform oracle buffer layout.