Requirements
- Target platform
- OpenClaw
- Install method
- Manual import
- Extraction
- Extract archive
- Prerequisites
- OpenClaw
- Primary doc
- SKILL.md
Tencent SkillHub · Data Analysis
MySQL
Write correct MySQL queries avoiding common pitfalls with character sets, indexes, and locking.
skill openclawclawhub Free
Write correct MySQL queries avoiding common pitfalls with character sets, indexes, and locking.
⬇ 0 downloads ★ 0 stars Unverified but indexed
Install for OpenClaw
Quick setup
- Download the package from Yavira.
- Extract the archive and review SKILL.md first.
- Import or place the package into your OpenClaw setup.
Package facts
- Download mode
- Yavira redirect
- Package format
- ZIP package
- Source platform
- Tencent SkillHub
- What's included
- SKILL.md, indexes.md, production.md, queries.md, transactions.md
Validation
- Use the Yavira download entry.
- Review SKILL.md after the package is downloaded.
- Confirm the extracted package contains the expected setup assets.
Install with your agent
Agent handoff
Hand the extracted package to your coding agent with a concrete install brief instead of figuring it out manually.
- Download the package from Yavira.
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New install
I downloaded a skill package from Yavira. Read SKILL.md from the extracted folder and install it by following the included instructions. Tell me what you changed and call out any manual steps you could not complete.
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I downloaded an updated skill package from Yavira. Read SKILL.md from the extracted folder, compare it with my current installation, and upgrade it while preserving any custom configuration unless the package docs explicitly say otherwise. Summarize what changed and any follow-up checks I should run.
Trust & source
Release facts
- Source
- Tencent SkillHub
- Verification
- Indexed source record
- Version
- 1.0.1
Provenance
- Publisher
- ivangdavila
- Source page
- View original listing
- Canonical URL
- Open canonical page
Documentation
Quick Reference
TopicFileIndex design deep diveindexes.mdTransactions and lockingtransactions.mdQuery optimizationqueries.mdProduction configproduction.md
Character Set Traps
utf8 is broken—only 3 bytes, can't store emoji; always use utf8mb4 utf8mb4_unicode_ci for case-insensitive sorting; utf8mb4_bin for exact byte comparison Collation mismatch in JOINs kills performance—ensure consistent collation across tables Connection charset must match: SET NAMES utf8mb4 or connection string parameter Index on utf8mb4 column larger—may hit index size limits; consider prefix index
Index Differences from PostgreSQL
No partial indexes—can't WHERE active = true in index definition No expression indexes until MySQL 8.0.13—must use generated columns before that TEXT/BLOB needs prefix length: INDEX (description(100))—without length, error No INCLUDE for covering—add columns to index itself: INDEX (a, b, c) to cover c Foreign keys auto-indexed only in InnoDB—verify engine before assuming
UPSERT Patterns
INSERT ... ON DUPLICATE KEY UPDATE—not standard SQL; needs unique key conflict LAST_INSERT_ID() for auto-increment—no RETURNING clause like PostgreSQL REPLACE INTO deletes then inserts—changes auto-increment ID, triggers DELETE cascade Check affected rows: 1 = inserted, 2 = updated (counter-intuitive)
Locking Traps
SELECT ... FOR UPDATE locks rows—but gap locks may lock more than expected InnoDB uses next-key locking—prevents phantom reads but can cause deadlocks Lock wait timeout default 50s—innodb_lock_wait_timeout for adjustment FOR UPDATE SKIP LOCKED exists in MySQL 8+—queue pattern InnoDB default isolation is REPEATABLE READ, not READ COMMITTED like PostgreSQL Deadlocks are expected—code must catch and retry, not just fail
GROUP BY Strictness
sql_mode includes ONLY_FULL_GROUP_BY by default in MySQL 5.7+ Non-aggregated columns must be in GROUP BY—unlike old MySQL permissive mode ANY_VALUE(column) to silence error when you know values are same Check sql_mode on legacy databases—may behave differently
InnoDB vs MyISAM
Always use InnoDB—transactions, row locking, foreign keys, crash recovery MyISAM still default for some system tables—don't use for application data Check engine: SHOW TABLE STATUS—convert with ALTER TABLE ... ENGINE=InnoDB Mixed engines in JOINs work but lose transaction guarantees
Query Quirks
LIMIT offset, count different order than PostgreSQL's LIMIT count OFFSET offset != and <> both work; prefer <> for SQL standard No transactional DDL—ALTER TABLE commits immediately, can't rollback Boolean is TINYINT(1)—TRUE/FALSE are just 1/0 IFNULL(a, b) instead of COALESCE for two args—though COALESCE works
Connection Management
wait_timeout kills idle connections—default 8 hours; pooler may not notice max_connections default 151—often too low; each uses memory Connection pools: don't exceed max_connections across all app instances SHOW PROCESSLIST to see active connections—kill long-running with KILL <id>
Replication Awareness
Statement-based replication can break with non-deterministic functions—UUID(), NOW() Row-based replication safer but more bandwidth—default in MySQL 8 Read replicas have lag—check Seconds_Behind_Master before relying on replica reads Don't write to replica—usually read-only but verify
Performance
EXPLAIN ANALYZE only in MySQL 8.0.18+—older versions just EXPLAIN without actual times Query cache removed in MySQL 8—don't rely on it; cache at application level OPTIMIZE TABLE for fragmented tables—locks table; use pt-online-schema-change for big tables innodb_buffer_pool_size—set to 70-80% of RAM for dedicated DB server
Category context
Data access, storage, extraction, analysis, reporting, and insight generation.
Source: Tencent SkillHub
Largest current source with strong distribution and engagement signals.
Package contents
Included in package
5 Docs
- SKILL.md
- indexes.md
- production.md
- queries.md
- transactions.md