MySQL Administration — Expert Reference

Use When

• Expert MySQL 8 administration: replication topology, InnoDB Cluster / Group Replication, security hardening, backup strategies with mysqldump/mydumper/xtrabackup, monitoring with Performance Schema, and production operations. Use when setting up...
• The task needs reusable judgment, domain constraints, or a proven workflow rather than ad hoc advice.

Do Not Use When

• The task is unrelated to mysql-administration or would be better handled by a more specific companion skill.
• The request only needs a trivial answer and none of this skill's constraints or references materially help.

Required Inputs

• Gather relevant project context, constraints, and the concrete problem to solve; load references only as needed.
• Confirm the desired deliverable: design, code, review, migration plan, audit, or documentation.

Workflow

• Read this SKILL.md first, then load only the referenced deep-dive files that are necessary for the task.
• Apply the ordered guidance, checklists, and decision rules in this skill instead of cherry-picking isolated snippets.
• Produce the deliverable with assumptions, risks, and follow-up work made explicit when they matter.

Quality Standards

• Keep outputs execution-oriented, concise, and aligned with the repository's baseline engineering standards.
• Preserve compatibility with existing project conventions unless the skill explicitly requires a stronger standard.
• Prefer deterministic, reviewable steps over vague advice or tool-specific magic.

Anti-Patterns

• Treating examples as copy-paste truth without checking fit, constraints, or failure modes.
• Loading every reference file by default instead of using progressive disclosure.

Outputs

• A concrete result that fits the task: implementation guidance, review findings, architecture decisions, templates, or generated artifacts.
• Clear assumptions, tradeoffs, or unresolved gaps when the task cannot be completed from available context alone.
• References used, companion skills, or follow-up actions when they materially improve execution.

Evidence Produced

Category	Artifact	Format	Example
Operability	Replication and backup runbook	Markdown doc per skill-composition-standards/references/runbook-template.md covering replication, failover, and restore-test procedure	docs/data/mysql-runbook.md

References

• Use the references/ directory for deep detail after reading the core workflow below.

1. my.cnf Production Baseline

[mysqld]
# --- Identity ---
server-id                        = 1          # unique per node
report_host                      = mysql-a    # used by InnoDB Cluster

# --- Character set ---
character_set_server             = utf8mb4
collation_server                 = utf8mb4_unicode_ci

# --- InnoDB memory ---
innodb_buffer_pool_size          = 10G        # 70% of available RAM
innodb_buffer_pool_instances     = 8          # 1 per GB of pool; reduces contention
innodb_log_buffer_size           = 48M        # larger for heavy write workloads

# --- InnoDB redo log (MySQL 8.0.30+) ---
innodb_redo_log_capacity         = 2G         # replaces innodb_log_file_size
# Legacy (pre-8.0.30): innodb_log_file_size=512M  innodb_log_files_in_group=2

# --- InnoDB durability ---
innodb_flush_log_at_trx_commit   = 1          # 1=ACID-safe; 2=faster, 1s risk
innodb_flush_method              = O_DIRECT   # bypass OS cache; avoids double-buffer
innodb_file_per_table            = ON         # one .ibd file per table
innodb_doublewrite               = ON         # crash-safe page writes (default)

# --- Connections ---
max_connections                  = 500
thread_cache_size                = 50
wait_timeout                     = 600        # idle non-interactive connection TTL
interactive_timeout              = 600

# --- Slow query log ---
slow_query_log                   = 1
slow_query_log_file              = /var/log/mysql-slow.log
long_query_time                  = 1          # seconds; lower in latency-sensitive systems
log_queries_not_using_indexes    = OFF        # enable when diagnosing index gaps

# --- Binary log (required for replication) ---
log-bin                          = mysql-bin
log-bin-index                    = mysql-bin.index
binlog_format                    = ROW        # safest for replication; required for GR
sync_binlog                      = 1          # flush binlog per commit; ACID-safe
expire_logs_days                 = 7

# --- GTID ---
gtid_mode                        = ON
enforce_gtid_consistency         = ON

# --- Network ---
bind-address                     = 127.0.0.1  # restrict to localhost; override for cluster

Key trade-offs:

• innodb_flush_log_at_trx_commit=2 improves throughput ~5-10x but risks up to 1s data loss on OS crash — replicas only
• innodb_dedicated_server=ON (8.0.30+): auto-sizes buffer pool and redo log — dedicated servers only

---

Additional Guidance

Extended guidance for mysql-administration was moved to references/skill-deep-dive.md to keep this entrypoint compact and fast to load.

Use that deep dive for:

• 2. GTID-Based Replication Setup
• 3. InnoDB Cluster (MySQL 8 AdminAPI)
• 4. Group Replication vs Async Replication
• 5. User Security Model — Principle of Least Privilege
• 6. Network Security
• 7. Audit Logging
• 8. Backup Strategy
• 9. Point-in-Time Recovery (PITR)
• 10. Monitoring Queries (Performance Schema)
• 11. Table Maintenance
• 12. Schema Changes in Production
• 13. Connection Pooling
• Additional deep-dive sections continue in the reference file.