What does "Table rewrite" mean?
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/9.5/static/sql-altertable.html Description: I see references to a "table rewrite" all over the place, but I cannot find one single definition on what that actually means. What does a table rewrite do? Does it drop and recreate the table? Everywhere I look people describe it with fear and trepedation as if it was some catastrophically dangerous operation to perform. What is it?
Re: What does "Table rewrite" mean?
=?utf-8?q?PG_Doc_comments_form?= writes: > What does a table rewrite do? Does it drop and recreate the table? > Everywhere I look people describe it with fear and trepedation as if it was > some catastrophically dangerous operation to perform. What is it? It means reading the whole table and writing it out in some modified form (for instance, with some column transformed into a new datatype). It's not "dangerous" in any way ... but if you've got many GB of data in the table and you can't afford to have the table locked for a long time, then it's something to avoid. regards, tom lane
Re: typo: overlay
On 1/18/18 13:35, PG Doc comments form wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/9.4/static/functions-string.html > Description: > > https://www.postgresql.org/docs/9.4/static/functions-string.html > > in the overlay example, there should only be 'xxx' instead of ''. (the > 'xxx' is being replaced with 'hom'.) The example correctly illustrates that the replacement string does not have to have the same length as the string being replaced. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
