asmhatreandClaude Sonnet 5
e478eafda3
Companion code for Zero-Downtime Database Migrations: Expand-Contract in Practice with Spring Boot: a full expand/migrate-writes/migrate-reads/contract sequence run as an actual rolling deploy across two live replicas, with a load generator sending continuous HTTP traffic through all four deploys (99.98% success, every residual error traced to a root cause rather than left unexplained). Findings include a real NOT NULL constraint trap in the expand migration, a backfill-window bug in the read switch, H2's AUTO_SERVER=TRUE single-point-of-failure behavior under a rolling restart, the drain-before-SIGTERM fix needed to close a health-check gap during graceful shutdown, and H2 silently discarding a concurrently committed INSERT during an ALTER TABLE ADD/DROP COLUMN rebuild - confirmed, by primary source, to be an H2-specific behavior rather than a property of the technique itself. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_019Fb7vW8vLyLKngBc4R3huA
15 lines
933 B
Plaintext
15 lines
933 B
Plaintext
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The NOT NULL trap: expand without relaxing the old column's constraint
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captured: 2026-09-16T19:21:04.662650854Z
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-- Stage 4 create() against the NAIVE migration (no DROP NOT NULL) --
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org.springframework.dao.DataIntegrityViolationException: PreparedStatementCallback; SQL [INSERT INTO customers(name, email_address) VALUES (?, ?)]; NULL not allowed for column "EMAIL"; SQL statement:
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INSERT INTO customers(name, email_address) VALUES (?, ?) [23502-240]
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root cause: org.h2.jdbc.JdbcSQLIntegrityConstraintViolationException: NULL not allowed for column "EMAIL"; SQL statement:
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INSERT INTO customers(name, email_address) VALUES (?, ?) [23502-240]
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-- Stage 4 create() against the SHIPPED V2 migration (DROP NOT NULL included) --
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Customer[id=1, name=On Time, [email protected]]
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