Discussion on the parallel sequential scan thread has revealed the need for a way to make dsm_create() return NULL, instead of failing, when we hit the system-wide maximum on the number of dynamic shared memory segments than can be created. I've developed a small patch for this which I attach here. It adds a second argument to dsm_create(), an integer flags argument. I would like to go ahead and commit this more or less immediately if there are not objections.
One question I struggled with is whether to keep the existing dsm_create() signature intact and add a new function dsm_create_extended(). I eventually decided against it. The dsm_create() API is relatively new at this point, so there probably aren't too many people who will be inconvenienced by an API break now. If we go ahead and create dsm_create_extended() now, and then need to make another API change down the line, I doubt there will be much support for dsm_create_extended2() or whatever. So my gut is that it's better to just change this outright, and keep dsm_create_extended() as an idea for the future. But I could go the other way on that if people feel strongly about it. Thanks, -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
dsm-create-flags.patch
Description: binary/octet-stream
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