1[WARNING] 2.A word about regular expression matching with timestrings 3========================================================== 4Timestrings are parsed from strftime patterns, like `%Y.%m.%d`, into regular 5expressions. For example, `%Y` is 4 digits, so the regular expression for that 6looks like `\d{4}`, and `%m` is 2 digits, so the regular expression is `\d{2}`. 7 8What this means is that a simple timestring to match year and month, `%Y.%m` 9will result in a regular expression like this: `^.*\d{4}\.\d{2}.*$`. This 10pattern will match any 4 digits, followed by a period `.`, followed by 2 digits, 11occurring anywhere in the index name. This means it _will_ match monthly 12indices, like `index-2016.12`, as well as daily indices, like 13`index-2017.04.01`, which may not be the intended behavior. 14 15To compensate for this, when selecting indices matching a subset of another 16pattern, use a second filter with `exclude` set to `True` 17 18[source,yaml] 19------------- 20- filtertype: pattern 21 kind: timestring 22 value: '%Y.%m' 23- filtertype: pattern 24 kind: timestring 25 value: '%Y.%m.%d' 26 exclude: True 27------------- 28 29This will prevent the `%Y.%m` pattern from matching the `%Y.%m` part of the 30daily indices. 31 32*This applies whether using `timestring` as a mere pattern match, or as part of 33date calculations.* 34========================================================== 35