Update CBO docs to list more supported statements

[rmloveland]

A bit more work to address #3998.

Summary of changes:

• Edit the 'Supported statements' section of the 'Cost-based
  Optimizer' page as follows:

  • Add FILTER per opt: add support for aggregate FILTER cockroach#34077

  • Add DELETE per opt: Prune Update and Upsert input columns cockroach#34522

  • Add INSERT .. ON CONFLICT variants per opt: Add optimizer support for UPSERT and INSERT..ON CONFLICT statements cockroach#33339

  • Remove experimental_optimizer_updates cluster setting (can't find
    a commit for this, but I don't see it in SHOW ALL output on my
    local build of yesterday's master, version number is
    v2.2.0-alpha.20181217-1096-gd104dcee69-dirty.

[cockroach-teamcity]

http://cockroach-docs-review.s3-website-us-east-1.amazonaws.com/9c77ef69738fbd25da23beb8dfed1f9ae3452151/

[cockroach-teamcity]

This change is 

[cockroach-teamcity]

http://cockroach-docs-review.s3-website-us-east-1.amazonaws.com/a3a12af542ca76c530a6e3d9b38e50732e5300b8/

[rmloveland]

Direct link to the changed section of the CBO page is here.

Andy, please let me know if there is:

• anything that is incorrect?
• anything I missed that should be here?

[jseldess]

LGTM

[andy-kimball]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @andy-kimball and @rmloveland)

---

v2.2/cost-based-optimizer.md, line 36 at r1 (raw file):

{% include copy-clipboard.html %}
~~~ sql
> EXPLAIN(OPT) SELECT l_shipmode, avg(l_extendedprice) from lineitem GROUP BY l_shipmode;

The default output of EXPLAIN(OPT) has changed to show much less detail. To show more verbosity, you can use EXPLAIN(OPT,VERBOSE) or EXPLAIN(OPT,TYPES). You'll need to update the sample output accordingly.

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v2.2/cost-based-optimizer.md, line 61 at r1 (raw file):

~~~

In contrast, this query returns `pq: unsupported statement: *tree.Insert`, which means that it will use the legacy heuristic planner instead of the cost-based optimizer:

This is no longer true, since INSERT is now supported by the CBO.

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v2.2/cost-based-optimizer.md, line 74 at r1 (raw file):

## Types of statements supported by the cost-based optimizer

The cost-based optimizer supports most SQL statements. Specifically, the following types of statements are supported:

I'd add the following to make this a more complete list:

• All SELECT statements that do not include window functions
• All UNION statements that do not include window functions
• All VALUES statements that do not include window functions

[rmloveland]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @andy-kimball)

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v2.2/cost-based-optimizer.md, line 36 at r1 (raw file):

Previously, andy-kimball (Andy Kimball) wrote…

The default output of EXPLAIN(OPT) has changed to show much less detail. To show more verbosity, you can use EXPLAIN(OPT,VERBOSE) or EXPLAIN(OPT,TYPES). You'll need to update the sample output accordingly.

I'm moving the work of updating this EXPLAIN output to #4348 in order to get the other updates live on the site for the alpha release this afternoon.

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v2.2/cost-based-optimizer.md, line 61 at r1 (raw file):
Fixed by updating that paragraph to avoid using an example since that will likely change again soon. Instead it now says

In contrast, queries that are not supported by the cost-based optimizer return errors that begin with the string pq: unsupported statement: ... or specific messages like pq: aggregates with FILTER are not supported yet. Such queries will use the legacy heuristic planner instead of the cost-based optimizer.

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v2.2/cost-based-optimizer.md, line 74 at r1 (raw file):

Previously, andy-kimball (Andy Kimball) wrote…

I'd add the following to make this a more complete list:

• All SELECT statements that do not include window functions
• All UNION statements that do not include window functions
• All VALUES statements that do not include window functions

Fixed by adding that information to the list - thanks Andy!

[cockroach-teamcity]

http://cockroach-docs-review.s3-website-us-east-1.amazonaws.com/c5fb63b8fca2998dbfc16384b178a751d5e8c98d/

[cockroach-teamcity]

http://cockroach-docs-review.s3-website-us-east-1.amazonaws.com/7fbce7b2580cab6109ecca90fbfaf5cf1b9fe9bc/