How to change the default collation of a table?

Breaking down collation alterations

Unraveling character sets and collation

Character sets categorize the symbols and encodings of a language. In contrast, collations are rules for comparing these characters. Altering table's collation can influence not only data ordering, but also how it's fetched and compared.

The clash of utf8 vs utf8mb4

In MySQL, opt for utf8mb4 in favor of utf8 for UTF-8 encoding. The former offers full support for Unicode characters — a feat utf8 falls short of, despite its deceiving name.

Changing collation for table and columns

To enforce a new collation on an entire table and its textual columns, utilize the ALTER TABLE ... CONVERT TO clause:

ALTER TABLE your_table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
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This ensures current and future columns obey the collation you've set.

Four levels of collation, like Shrek's layers of onions

MySQL collation operates on four planes of scope:

1. Server: Sets the course for new databases.
2. Database: Dictates the collation for all new tables and columns.
3. Table: Controls the collation for all new columns (reshapes existing ones with CONVERT TO).
4. Column: Influences data handling on the column level.

Applying the ALTER SCHEMA statement sets a new collation for all future tables and their columns in a specific database:

ALTER SCHEMA database_name DEFAULT COLLATE utf8mb4_unicode_ci;
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Fine-tuning individual columns

When not all columns need to change, attend to each one with care:

ALTER TABLE your_table_name MODIFY COLUMN column_name VARCHAR(255)
COLLATE utf8mb4_unicode_ci;
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When going this route, check that the new collation doesn't clash with your planned usages.

Avoiding common traps

• Syntax is king: Triple-check the command syntax — no typos allowed.
• Time-travelling: Be aware that some collations and features might be ghosts in older versions.
• Defaults can be sneaky: Changing default table collation doesn't retroactively update existing columns. Emberace explicit column alterations.

Deep insights and best practices for collation

Setting a winning strategy for collation changes

• Assessment first: Understand your data use case and select a fitting collation. Do you prefer language-specific or universal sorting?
• Compatibility is key: Collation must be compatible with your application's standards and your database's version.
• Test, don't guess: Implement your changes in a development environment before production — surprises can be fun, but not in a live database!

Performance tuning with collation tweaks

• Managing indexes: Changes in collations can influence index performance. Sorting data differently can have consequences!
• Length matters: Larger character sets like utf8mb4 may require more storage and impact speed — design your schema conscientiously.

Maintenance and growth

• Community gems: Keep an eye on community feedback and recommendations — don't reinvent the wheel where it's not necessary!
• Be a documents explorer: Always refer to the latest database documentation for guidance on collations. Changes happen and you want to be informed!