[CALCITE-4763] add EXISTS_AGG aggregate function

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: xiong duan
• Reporter: Julian Hyde
• Created: 03/Sep/21 01:03
• Updated: 20/Sep/21 01:22

Description

Add EXISTS_AGG, an aggregate function that returns whether count is greater than zero.

Thus EXISTS_AGG(*) is equivalent to COUNT(*) > 0, and EXISTS_AGG(c) is equivalent to COUNT(c) > 0.

EXISTS_AGG would mainly be of use internally. Since it produces a BOOLEAN value, we can use the value directly from an Aggregate without an intervening Project. It also captures the fact that we don't care how many rows were produced.

See also TRUE_AGG, CALCITE-4334.

Issue Links

• relates to: CALCITE-4334 LITERAL_AGG, an aggregate function that returns a constant value
• links to: PR-2528