Disable nonblocking mode while large object calls #498
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libpq's "lo_*" calls fail when a bigger amount of data is transferred and the connection is set to nonblocking mode. According to some discussion here https://www.postgresql.org/message-id/20130606.082048.998330612674120762.t-ishii%40sraoss.co.jp the large object interface isn't intended to be used with nonblocking mode. It works to some extend with small data (< 8000 Bytes), but fails after lo_write of bigger data at the next exec call on the same connection like so: ``` message type 0x56 arrived from server while idle message type 0x5a arrived from server while idle message type 0x43 arrived from server while idle message type 0x5a arrived from server while idle PG::UnableToSend: unexpected response from server; first received character was "V" ``` I think the best solution is to disable nonblocking mode for the time of the lo_* call. Calling PQisnonblocking and PQsetnonblocking is very low overhead, since these functions do a few memory operations only. Fixes ged#460
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This came up here: lsylvester/active_storage-postgresql#16 It fails for me with the
unexpected response from server; first received character was "V"in their test suite.libpq's "lo_*" calls fail when a bigger amount of data is transferred and the connection is set to nonblocking mode. According to some discussion here
https://www.postgresql.org/message-id/20130606.082048.998330612674120762.t-ishii%40sraoss.co.jp
the large object interface isn't intended to be used with nonblocking mode.
It works to some extend with small data (< 8000 Bytes), but fails after lo_write of bigger data at the next exec call on the same connection like so:
I think the best solution is to disable nonblocking mode for the time of the lo_* call. Calling PQisnonblocking and PQsetnonblocking is very low overhead, since these functions do a few memory operations only.
Fixes #460
/CC @Nerian