external/og-aws
1
0
Fork 0
mirror of https://github.com/nickpoida/og-aws.git synced 2025-02-13 10:21:57 +00:00
Code Issues Releases Wiki Activity

Changes requested for pr

Browse source
This commit is contained in:
Halil Duygulu 2016-10-17 14:00:44 +03:00
parent 71b3cbc0fd
commit 12f149dfde
1 changed files with 2 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
README.md
View file

@ -1252,9 +1252,8 @@ Redshift
- ❗ Never resize a live cluster. The resize operation takes hours depending on the dataset size. In rare cases, the operation may also get stuck and you'll end up having a non-functional cluster. The safer approach is to create a new cluster from a snapshot, resize the new cluster and shut down the old one.
- Redshift has reserved keywords which are not present in Postgres (see full list [here](https://docs.aws.amazon.com/redshift/latest/dg/r_pg_keywords.html)). Watch out for DELTA ([Delta Encodings](https://docs.aws.amazon.com/redshift/latest/dg/c_Delta_encoding.html)).
- Redshift does not support many Postgres functions, most notably several date/time-related and aggregation functions. See the [full list here](https://docs.aws.amazon.com/redshift/latest/dg/c_unsupported-postgresql-functions.html).
- 🔹 If you need to change sort key or dist key of a table, you need to create a new table with new key and move your data to new table with insert into new_table select * from old_table. [Choosing Sort Key](http://docs.aws.amazon.com/redshift/latest/dg/t_Sorting_data.html)
- ❗🚪 When moving data with insert into x select from y; you need to have at least twice of y table size free space on your harddisk. Redshift first copies data to disk then to new table.
- 🔹 Vacuum delete only does not block copy commands, but vacuum reindex can block if you execute copy command every minute or so.
- 🔹 [Choosing Sort Key](http://docs.aws.amazon.com/redshift/latest/dg/t_Sorting_data.html) is very important since you can not change sort key after table created. If you need to change sort key or distribution key of a table, you need to create a new table with new key and move your data into it with a query like "insert into new_table select * from old_table".
- ❗🚪 When moving data with a query that looks like “insert into x select from y;” you need to have as twice as much space as table “y” takes up available on your cluster's disk. Redshift first copies the data to disk and then to the new table. A good [article](https://www.periscopedata.com/blog/changing-dist-and-sort-keys-in-redshift.html) about how to this for big tables.
EMR
---