gp_distribution_policy |字段名|描述| |---|---| |localoid|表的OID| |policytype|分布类型'p'分区'r'复制表| |numsegments|表分布在多少个节点上| |diskkey|分布列的序号| |distclass|分布列的操作类| ## GPExpand简介与具体用法 - GPExpand是Greenplum的扩容工具 扩容后，新节点没有数据，查询Plan如何做？？？ - 在Greenplum 5和之前的版本里会将所有的表改成随机分布，然后再ALTER成按列分布 Greenplum 6里引入了numsegments Numsegments描述了该表连续分布的segment数量，默认与集群大小一致。对每个表执行操作时也会按照numsegment值分配Gang 增加新节点后，对每个表做EXPAND后该值会随着改成新集群的大小 table; ALTER TABLE gpadmin=# select * from gp_distribution_policy; localoid | policytype | numsegments | distkey | distclass 16388 | p | 3 | 1 | 10027 16385 | p | 4 | 1 | 10027 (2 rows) T1上的查询(未做重分布)

不过，EXPAND TABLE不再是简单的REORGANIZE，这与6之前的版本不同，6版本开始，因为要支持真正意义上的在线扩容，通过gp_distribution_policy系统表的numsegments字段来识别一张表是否已经完成扩容的数据重分布操作。 ### 4. 清理用于扩容的gpexpand模式。 $ gpexpand -c 对于6版本来说，扩容操作不需要重启数据库，但是，对于使 版本，不再需要将表的分布策略修改为RANDOMLY，而是通过gp_distribution_policy系统表的numsegments字段来标识表的数据分布情况，在未进行重分布之前，numsegments字段的值与原有集群的Primary数量相等，完成重分布之后，numsegments字段的值与扩容后的Primary数量相等。 qpexpand.expansion_progress是一个视图，用于查看数据重分布的进度。 样写的： population of status_detail for partitioned tables, leaf partition cannot has different numsegments with root partition, we need to expand root partition in one shot, so just populate root partition

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. Resolves a PL/pgSQL function infinite recursion issue by always writing a snapshot

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. 12871 : Resolves a PL/pgSQL function infinite recursion issue by always writing a

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. 12871 : Resolves a PL/pgSQL function infinite recursion issue by always writing a

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. Resolves a PL/pgSQL function infinite recursion issue by always writing a snapshot

instances.• r - Replicated policy. Table data is replicated on each segment instance.numsegmentsintegerThe number of segment instances on which the table data is distributed menameThe name of this Greenplum Database system.numsegmentsintegerThe number of segments in the Greenplum Database system.

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. 12871 Resolves a PL/pgSQL function infinite recursion issue by always writing a snapshot

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. 12871 Resolves a PL/pgSQL function infinite recursion issue by always writing a snapshot

The issue occurred when path nodes with bottleneck locus types (Entry and SingleQE), and equal numsegments, were moved. 12871 Resolves a PL/pgSQL function infinite recursion issue by always writing a snapshot