postgresql 查找PL/PGSQL函数以返回N列如果不在某个地方对列列表进行硬编码（无论是在调用函数时还是在定义函数时），就无法创建返回动态列数的函数。我看到的最好的（唯一的）选项是创建一个基于表内容的视图，然后每次表更改时都可以调用该视图来创建一个具有更新的列列表的新视图。
alignment (to make sure the next column starts at a multiple of CPU-word length) Now imagine what that means if we need to loop over 1000 columns? It does create some non-trivial overhead. Finally … The key insight here is that using extremely large tables is often not beneficial from...
(2rows) SELECT*FROMpersonWHEREcurrent_mood>'sad'ORDERBYcurrent_mood; name|current_mood ---+--- Curly|ok Moe|happy (2rows) SELECTname FROMperson WHEREcurrent_mood=(SELECTMIN(current_mood)FROMperson); name --- Larry (1row) 地理位置类型 网络地址类型 inet 和 cidr 的区别 二者最关键的区别在...
table_and_columns是啥? 指的是垃圾回收可以指定表以及列,如果不想对所有表做清理,在手动清理的时候可以进行配置。 此外Postgresql针对垃圾回收开发了另一个子命令VACUUM ANALYZE, 可以通过此命令对于运行的 Postgresql 实例进行分析,也是实现自动垃圾回收的关键组件之一。
Column aliases –learn how to assign temporary names to columns or expressions within a query. Order By –guide you on how to sort the result set returned by a query. Select Distinct –show you how to remove duplicate rows from the result set. Section 2. Filtering Data Where –filter rows...
Fixed an issue with multiple parentheses in SELECT columns. Fixed an issue with handling of column name alias which may cause client to hang if column name alias contains string of length more than 64 bytes, for example, select col as '您对“数据一览“中的车型,颜色,内饰,选装, '. Fixed ...
w.classid and r.objid is not distinct from w.objid and r.objsubid is not distinct from w.objsubid and r.transactionid is not distinct from w.transactionid and r.pid <> w.pid order by f_lock_level(w.mode)+f_lock_level(r.mode) desc,r.xact_start LOOP raise notice '%', v_...
Add columns to pg_stat_replication to report replication delay times (Thomas Munro) The new columns are write_lag, flush_lag, and replay_lag. Allow specification of the recovery stopping point by Log Sequence Number (LSN) in recovery.conf (Michael Paquier) Previously the stopping point could ...
Multicolumn indexes are supported, but it is worth mentioning that the order of their columns is irrelevant. Unlike a regular B-tree, a multicolumn GIN index does not store composite keys; instead, it extends separate elements with the corresponding column number. 但支持多列索引,但值得一提的是...
last_namematches all columns namedlast_nameandusers.last_namematches only the users table. Wildcards are supported, and the first matching rule is applied. Options for replacement are: unique_email unique_phone unique_secret random_letter