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https://www.postgresql.eu/events/pgconfeu2017/schedule/session/1585-be-pro-activ-on-postgresql-performance/ https://www.postgresql.eu/events/pgconfeu2 阅读全文
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What NamedTuplestore 按字面意思理解,就是一个有名字的 tuplestore, 那估计就不是一个正常的表。根据 PostgreSQL 的官方叫法,NamedTuplestoreScan 对应的表称为 Ephemeral Named Relation, 中文翻译为 短暂的命名关系. 阅读全文
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One sentence summary A temporary table could reside within a temporary tablespace, utilizing a temporary name in a temporary schema or namespace. More 阅读全文
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Since version 14, gdb has a new interpreter 'dap'. With this new feature, we can debug c/c++/rust code within neovim without using other tools. build 阅读全文
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The following sql statements will trigger calling function GetExistingLocalJoinPath. setup CREATE EXTENSION postgres_fdw; CREATE SERVER foreign_server 阅读全文
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The SQL select sum(sum(a)) from myt1 group by a; This note focuses only on sum(sum(a)) and it's about how postgres rejects the sql above. Notes sum(su 阅读全文
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This note will introduce the workflow of parse.pl of the ecpg precompiler. Run the precompiler: perl parse.pl . ../../../backend/parser/gram.y workflo 阅读全文
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背景 在如下的 sql 中, select rowid from (select 1 from t); lightdb 24.1 以前会直接报错,说找不到 rowid 列。为了兼容 Oracle, 在 24.1 中,我们选择将告知子查询除了返回子查询应有的列之外,还需返回 rowid 列。 样例 以 阅读全文
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The SQL select a from (select a from t); Overview from (select a from t) will map to one RangeTblEntry struct of the outter query. from t will map to 阅读全文
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背景 Oracle 中支持很多种分区管理操作。其中 merge partitions 会将多个连续分区合并成一个分区。lightdb 24.1 中支持了该功能。 merge partitions 功能支持 list 和 range 分区,不支持 hash 分区。 用例 range 分区 CREATE 阅读全文