[PHOENIX-6127] Prevent unnecessary HBase admin API calls in ViewUtil.getSystemTableForChildLinks() and act lazily instead

• Type: Improvement
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 5.0.0, 4.15.0
• Fix Version/s: 4.17.0
• Labels: phoenix-hardening quality-improvement
• Assignee: Richárd Antal
• Reporter: Chinmay Kulkarni
• Created: 12/Sep/20 00:27
• Updated: 25/Feb/21 02:31

Description

In order to handle the case of older clients connecting to a 4.16 cluster that has old metadata (no SYSTEM.CHILD_LINK table yet), we call ViewUtil.getSystemTableForChildLinks() to figure out whether to use SYSTEM.CHILD_LINK or SYSTEM.CATALOG to look up parent->child linking rows.

Here we do HBase table existence checks using HBase admin APIs (see this) which can be avoided. In almost all cases once we've called this API, we later go on and retrieve the Table object anyhow so we can instead try to always get the SYSTEM.CHILD_LINK table and if that fails, try to get SYSTEM.CATALOG. This will avoid additional admin API calls.

Issue Links

• links to: GitHub Pull Request #944