Feature #4854
open
Feature #4566: pgsql: add subprotocol-states
pgsql: Add COPY subprotocol-state
Added by Juliana Fajardini Reichow over 3 years ago.
Updated 3 days ago.
Description
When the postgresql backend sends or receives the following commands:
- "COPY FROM STDIN"
- "COPY TO STDOUT"
It enters the COPY subprotocol-state, which comprises a different set of messages.
Currently, if Suri has the pgsql app-layer enabled and sees one of those messages, it doesn't know what to do and stops parsing pgsql messages from that flow altogether, afterwards.
PostgreSQL documentation: https://www.postgresql.org/docs/14/protocol-flow.html#PROTOCOL-COPY
Files
- Subject changed from PGSQL app-layer-parser: Add COPY subprotocol to PGSQL app-layer-parser: Add COPY subprotocol-state
- Description updated (diff)
Updating this to better word that these are postgresql subprotocols, which are somewhat interpreted as sub-states, by Suri.
- Subject changed from PGSQL app-layer-parser: Add COPY subprotocol-state to pgsql: Add COPY subprotocol-state
- Target version changed from 7.0.0-beta1 to 7.0.0-rc1
- Target version changed from 7.0.0-rc1 to 8.0.0-beta1
- Priority changed from Normal to High
- Status changed from New to In Progress
The COPY operations can be split into three different modes (cf https://www.postgresql.org/docs/13/protocol-flow.html#PROTOCOL-COPY):
- Copy-In mode - high-speed bulk data transfer to the server
- Copy-Out mode - high-speed bulk data transfer from the server
- Copy-Both - high-speed bulk data transfer to and from the server
Copy-In and Copy-Out operations will lead the backend (server) to switch to dedicated subprotocols that will last until the operation is completed (either with a Success or a Failure).
Those operations can be sent from either Simple Query or Extended Query modes.
Due to PostgreSQL protocol specifications, the Copy-Out sub-proto seems a bit easier to implement, as the backend will send one CopyData message per copied row, whereas there is no such guarantee in the specification for CopyData messages coming from the frontend.
So I'll start with the Copy-Out sub-protocol/ mode.
Simple-ish sequence diagram for the Copy-In mode
Simple-ish sequence diagram for the Copy-Out mode
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