SQL
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count(*) OVER () or Repeatable Read for a paged report
Read Committed lets a paged report disagree with itself. The reporting screen counts 12 matching orders. Another session comm…
rows.Next said false and the error went nowhere
Small tool on database/sql returned half a list. No error. The code. Context with a deadline. The deadline fired in the middl…
count(*) arrived as a string and 12 + 1 made 121
A todo list screen. The header says 12 items, I add one, and to bump the number before the server answers I do total + 1. The…
NOT IN and one NULL
SELECT * FROM orders o WHERE o.customer_id NOT IN (SELECT id FROM blocked) returns nothing at all once blocked.id holds a sin…
A partial index and a parameter in the WHERE clause
A partial index is used only when the planner can show that the query's WHERE implies the index predicate. The docs say the m…
SKIP LOCKED job queue and a worker that dies mid-transaction
Job queue straight in a table. One worker in Python, one in Go. BEGIN, then SELECT id, payload FROM jobs WHERE status = 'queu…
UPDATE rechecks its WHERE after the wait
Two sessions under PostgreSQL Read Committed, one account with a balance of 15, and both sessions run the same statement. Ses…
COUNT(col) changed what a ratio meant
A report showed the share of orders with a shipping date as COUNT(shipped_at) * 1.0 / COUNT(*). It was right for a while. The…
Should a Rego allow rule default to false?
{"approved": false} and {} get the same answer from allow if input.approved == true. The answer is undefined, not false. The…
ON CONFLICT DO NOTHING and retried jobs
Answering every unique key conflict with "already accepted" hides three different situations. Two servers, one PostgreSQL tab…
