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[TOC] Summary The newly installed green plus cluster has only primary nodes and no mirror. High availability is not guaranteed. So you need to add mirror nodes to the cluster Note: When the amount of data is too large, adding mirror will result in greater disk pressure, because the background will always synchronize the data, which online syste ...

1,Subquery 1.1,Introduction to Subqueries 1.2,WITH Subquery 2,Aggregate query 2.1,UNION and UNION ALL 2.2,MINUS 2.3,INTERSECT 2.4,Set Operations and ORDER BY 3,DISTINCT clause 3.1,General usage 3.2,Parameters for aggregation functions 4,summary 1. Subquery 1.1. Introduction to Subqueries A sub-query is a query nested in SE ...

1. Installation Dependence yum install gcc gcc-c++ make readline-devel flex zlib-devel 2. Download the source code and decompress it Create Source Storage Directory mkdir -p /usr/local/src cd /usr/local/src Download decompression wget -c https://ftp.postgresql.org/pub/source/v10.0/postgresql-10.0.tar.gz tar -zxvf postgresql-10.0.tar.gz cd postg ...

Label PostgreSQL, 10.0, Radix tree, character encoding conversion background PostgreSQL 10.0 uses radix tree to improve the performance of UTF-8 and other character encoding conversions. The encoding map file is arranged according to the new radix tree, and its performance is much better than that of binary search. Use radix tree for charact ...

Label PostgreSQL, update from, one-to-many background First of all, table A and table B need related columns. After association, table A and table B should have a one-to-one or one-to-one relationship. If one-to-one, it is easy to understand. What if it's one-to-many? Any database will give you an uncertain answer (related to the scanning me ...

Label PostgreSQL , 10.0 , pg_xact , pg_wal , log , pg_clog , pg_xlog , pg_log background 10.0 renamed several directories with certain ambiguities. They are respectively pg_xlog, pg_clog, pg_log Renamed pg_wal, pg_xact, log They correspond to WAL (write ahead log) log, transaction status log and log respectively. It saves people from deletin ...

Label PostgreSQL, aggregation, filter, order, within group background PostgreSQL has powerful analysis functions, such as supporting multi-dimensional analysis, supporting four kinds of aggregation, supporting window query, supporting recursive query and so on. For the use of four major types of aggregation, please refer to <PostgreSQL ag ...

Label PostgreSQL, Linux, page allocation failure, memory background Linux kernel allocation fails. After using a certain amount of memory, HANG. There may be similar errors in dmesg, system HANG live, can not connect, need to restart to solve. page allocation failure Oct 24 11:27:42 kernel: : [21289.479063] python2.6: page allocati ...

postgresql has provided rollup/cube/grouping sets grouping functions since 9.5, which is more convenient to use. Especially when sql is used directly to produce reports, one sql can get all the details and summary values. https://www.postgresql.org/docs/9.5/static/sql-select.html https://www.postgresql.org/docs/9.5/static/queries-table-expres ...

PostgreSQL & PostGIS Install postgresql After configuring the yum source, you can find that the version of PostgreSQL is 9.2.23 by using yum info postgresql. If you want to install the latest version, you can refer to the following operation https://www.postgresql.org/download/linux/redhat/ http://docs.nextgis.com/docs_ngweb/source/install ...