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
18 lines
768 B
Plaintext
18 lines
768 B
Plaintext
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Deploy 2 (MIGRATE WRITES): Stage 2 writes land in both columns
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captured: 2026-09-16T19:21:04.333919632Z
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-- after create() --
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NAME | EMAIL | EMAIL_ADDRESS
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------------------+-----------------------+----------------------
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Margaret Hamilton | [email protected] | [email protected]
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(1 row)
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-- after updateEmail() - the old value is gone from BOTH columns, not just one --
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NAME | EMAIL | EMAIL_ADDRESS
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------------------+-------------------------+------------------------
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Margaret Hamilton | [email protected] | [email protected]
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(1 row)
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