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
17 lines
819 B
Bash
Executable File
17 lines
819 B
Bash
Executable File
#!/usr/bin/env bash
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# Starts H2 as its own standalone TCP server process - not owned by, or co-located
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# inside, either app replica. This is what a real production database is: a process
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# that outlives every app deploy. See docs/12-the-auto-server-trap.md for what went
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# wrong the first time this demo shared a database file directly between the two
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# replicas instead.
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set -euo pipefail
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DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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source "$DIR/env.sh"
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nohup java -cp "$(cat "$CP_FILE")" org.h2.tools.Server \
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-tcp -tcpPort "$EC_DB_TCP_PORT" -baseDir "$EC_DB_BASE_DIR" -ifNotExists \
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> "$EC_LOG_DIR/db-server.log" 2>&1 < /dev/null &
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echo $! > "$EC_PID_DIR/db-server.pid"
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wait_db_server
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echo "H2 TCP server up on port $EC_DB_TCP_PORT (pid $(cat "$EC_PID_DIR/db-server.pid")), baseDir $EC_DB_BASE_DIR"
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