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由 Richard Guo 提交于
This is the final batch of commits from PostgreSQL 9.2 development, up to the point where the REL9_2_STABLE branch was created, and 9.3 development started on the PostgreSQL master branch. Notable upstream changes: * Index-only scan was included in the batch of upstream commits. It allows queries to retrieve data only from indexes, avoiding heap access. * Group commit was added to work effectively under heavy load. Previously, batching of commits became ineffective as the write workload increased, because of internal lock contention. * A new fast-path lock mechanism was added to reduce the overhead of taking and releasing certain types of locks which are taken and released very frequently but rarely conflict. * The new "parameterized path" mechanism was added. It allows inner index scans to use values from relations that are more than one join level up from the scan. This can greatly improve performance in situations where semantic restrictions (such as outer joins) limit the allowed join orderings. * SP-GiST (Space-Partitioned GiST) index access method was added to support unbalanced partitioned search structures. For suitable problems, SP-GiST can be faster than GiST in both index build time and search time. * Checkpoints now are performed by a dedicated background process. Formerly the background writer did both dirty-page writing and checkpointing. Separating this into two processes allows each goal to be accomplished more predictably. * Custom plan was supported for specific parameter values even when using prepared statements. * API for FDW was improved to provide multiple access "paths" for their tables, allowing more flexibility in join planning. * Security_barrier option was added for views to prevents optimizations that might allow view-protected data to be exposed to users. * Range data type was added to store a lower and upper bound belonging to its base data type. * CTAS (CREATE TABLE AS/SELECT INTO) is now treated as utility statement. The SELECT query is planned during the execution of the utility. To conform to this change, GPDB executes the utility statement only on QD and dispatches the plan of the SELECT query to QEs. Co-authored-by: NAdam Lee <ali@pivotal.io> Co-authored-by: NAlexandra Wang <lewang@pivotal.io> Co-authored-by: NAshwin Agrawal <aagrawal@pivotal.io> Co-authored-by: NAsim R P <apraveen@pivotal.io> Co-authored-by: NDaniel Gustafsson <dgustafsson@pivotal.io> Co-authored-by: NGang Xiong <gxiong@pivotal.io> Co-authored-by: NHaozhou Wang <hawang@pivotal.io> Co-authored-by: NHeikki Linnakangas <hlinnakangas@pivotal.io> Co-authored-by: NJesse Zhang <sbjesse@gmail.com> Co-authored-by: NJinbao Chen <jinchen@pivotal.io> Co-authored-by: NJoao Pereira <jdealmeidapereira@pivotal.io> Co-authored-by: NMelanie Plageman <mplageman@pivotal.io> Co-authored-by: NPaul Guo <paulguo@gmail.com> Co-authored-by: NRichard Guo <guofenglinux@gmail.com> Co-authored-by: NShujie Zhang <shzhang@pivotal.io> Co-authored-by: NTaylor Vesely <tvesely@pivotal.io> Co-authored-by: NZhenghua Lyu <zlv@pivotal.io>
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