On 18.11.25 15:15, Heikki Linnakangas wrote:
Instead of a hash table to hold the values, you could have a dynamically
extendable "struct". DefineCustomXXXVariable can reserve an offset and
store it in a global variable. So the code to read the current GUC value
would look something like this:
/* defined elsewhere */
struct Session {
...
/* this area holds all the GUC values for the current session */
char *guc_values;
}
_Thread_local struct Session *session;
/* global variable set by DefineCustomBooleanVariable */
size_t enable_seqscan_offset;
The way I understand this, this would only work if
DefineCustomXXXVariable could only be called from a global context
(e.g., shared_preload_libraries). But AFAICT, you can define custom GUC
parameters per session (e.g., LOAD 'auto_explain'), and so each session
would have a different offset, and so the offset variable would itself
have to be session-local.
