chore: add full window bounds support to pull queries #4404

fixes: confluentinc#3871 Is needed to fix: - confluentinc#3633 - confluentinc#4015 Before this change the version of `ROWKEY` copied to the value schema during processing of data in the Streams topology was always of type `STRING` regardless of the actual key type. This is because windowed keys had a `ROWKEY` in the format `<actual key> : Window{start=<windowStart>, end=<windowEnd>}`. While `ROWKEY` in the value schema was a `STRING`, `ROWKEY` in the key schema was the actual type, e.g. `INT`. This is confusing and will lead to bugs. Also, the formated string isn't very friendly for users. This change looks to introduce the `WINDOWSTART` and `WINDOWEND` columns that were reserved in confluentinc#4388. The obvious approach would be to add `WINDOWSTART` and `WINDOWEND` as columns in the key schema. Unfortunately, this would be a much bigger change as many parts of the code currently rely on there being only a single key column. The planned structured key work will resolve this. For now, we only add the windows bounds columns when we `LogicalSchema.withMetaAndKeyColsInValue(true)`. This is a bit of a temporary hack, but gets us where we need to be. This will be cleaned up as part of the structured key work. With this change `ROWKEY` for windowed sources no longer has the format `<actual key> : Window{start=<windowStart>, end=<windowEnd>}`: `ROWKEY` is now only the _actual_ key and the window bounds can be accessed by `WINDOWSTART` and `WINDOWEND`. These two window bounds columns are included in a pull `SELECT *` query. Likewise a join will include the window bounds columns from both sides in the join result if the join is `SELECT *`. ## Examples: ### Push queries * A select * on a windowed source will not include `WINDOWSTART` and `WINDOWEND`. `ROWKEY` will be the actual key, not a formatted string. ``` ksql> SELECT * FROM windowedSource emit changes -- old output +---------------+------------------------------------------------------+--------+---------+------+ | ROWTIME | ROWKEY | USERID | PAGEID | TOTAL| +---------------+------------------------------------------------------+--------+---------+------+ | 1557183929488 | User_9|+|Page_39 : Window{start=1557183900000 end=-} | User_9 | Page_39 | 1 | | 1557183930211 | User_1|+|Page_79 : Window{start=1557183900000 end=-} | User_1 | Page_79 | 1 | -- new output +---------------+---------------+---------------+------------------+--------+---------+------+ | ROWTIME | WINDOWSTART | WINDOWEND | ROWKEY | USERID | PAGEID | TOTAL| +---------------+---------------+---------------+------------------+--------+---------+------+ | 1557183919786 | 1557183900000 | 1557183960000 | User_5|+|Page_12 | User_5 | Page_12 | 1 | | 1557183929488 | 1557183900000 | 1557183960000 | User_9|+|Page_39 | User_9 | Page_39 | 1 | ``` * `WINDOWSTART` and `WINDOWEND` are available in the SELECT, GROUPBY, WHERE, HAVING clauses etc. For example: ```sql SELECT TIMESTAMPTOSTRING(WINDOWSTART,'yyyy-MM-dd HH:mm:ss Z') FROM windowedSource emit changes; ``` However, don't get too excited just yet as there is a known limitation that drastically reduces the availability of this syntax: **KNOWN LIMITATION** Where a query builds a windowed source from a non-windowed source the window bounds columns are not available. For example: ``` -- won't yet work: SELECT WINDOWSTART FROM FROM someSource WINDOW TUMBLING (SIZE 1 SECOND) group by ROWKEY; ``` This issue is tracked by: confluentinc#4397 * Joins of windowed sources include the `WINDOWSTART` and `WINDOWEND` columns from both sides. ### Pull queries **KNOWN LIMITATION** Pull queries have not been updated yet. This will be done in a follow up PR confluentinc#3633. This is mainly to keep this PR manageable. ### Persistent queries Persistent C*AS queries work similar to push queries and have the same known limitation. BREAKING CHANGE: Any query of a windowed source that uses `ROWKEY` in the SELECT projection will see the contents of `ROWKEY` change from a formatted `STRING` containing the underlying key and the window bounds, to just the underlying key. Queries can access the window bounds using `WINDOWSTART` and `WINDOWEND`. BREAKING CHANGE: Joins on windowed sources now include `WINDOWSTART` and `WINDOWEND` columns from both sides on a `SELECT *`.

KSQL does support `<` operator for strings... revert doc change & add test

fixes: confluentinc#3633 This change sees pull queries share more functionality and code around the window bounds columns `WINDOWSTART` and `WINDOWEND` introduced in confluentinc#4388 and confluentinc#4401. * pull queries on time windowed sources, i.e. `TUMBLING` and `HOPPING`, now have a `WINDOWEND` in their schema, just like `SESSION` and the new push query functionality. * window bound columns are now accessible within the projection of a pull query, e.g. `SELECT WINDOWSTART, WINDOWEND FROM FOO WHERE ROWKEY=1;`

Conflicting files docs-md/developer-guide/create-a-stream.md docs-md/developer-guide/create-a-table.md

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chore: add full window bounds support to pull queries #4404

chore: add full window bounds support to pull queries #4404

Commits on Jan 29, 2020