These locks are acquired when rows are being updated (or deleted or marked for update). Row-level locks do not affect data querying. They block writers to the same row only. PostgreSQL does not remember any information about modified rows in memory and so has no limit to the number of

PostgreSQL and Query Processing PostgreSQL is NOT an exception to it as it also uses those standards. PostgreSQL conforms to SQL standard is ISO/IEC 9075 “Database Language SQL”. A revised version of the standard is released from time to time; the most recent update appearing in 2016. The 2016 version