perf: Speed up create_hogql_database

[timgl]

Problem

create_hogql_database is slow (somewhere between 1-1.5 seconds per run for team 2), and we run it multiple times for a single query.

This should make every query we run 1-2 seconds faster.

Changes

• add caching to create_initial_channel_type (on average this takes 0.3 seconds)
• make sure we only run create_hogql_database once

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

Does this work well for both Cloud and self-hosted?

How did you test this code?

[mariusandra]

Makes sense, though seems to have broken some tests. I assume the issues is that some tests flipping between PoE modes and other modifiers didn't discard self.database somewhere.

[robbie-c]

General principle sounds good!

To "yes and" this - I'd guess that most of the 0.3 seconds in create_initial_channel_type comes from parsing HogQL, if we had a good pattern for caching the results of parsing HogQL in general (before team-specific context or placeholder values were applied) we could probably find similar speedups in a bunch of trends and web analytics queries

[sentry-io]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ AlertCheckException: unhashable type: 'list' posthog.tasks.alerts.checks.check_alert_task View Issue
• ‼️ TypeError: unhashable type: 'list' /api/environments/{parent_lookup_team_id}/query/ View Issue
• ‼️ TypeError: unhashable type: 'list' posthog.tasks.tasks.process_query_task View Issue
• ‼️ TypeError: unhashable type: 'list' posthog.caching.warming.warm_insight_cache_task View Issue
• ‼️ TypeError: unhashable type: 'list' posthog.caching.warming.warm_insight_cache_task View Issue

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