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Displaying posts with tag: datatypes (reset)
MySQL 8.0: Removing support for old temporal datatypes

MySQL 5.6 introduced  the fractional second precision for temporal data types – TIME, DATETIME, and TIMESTAMP,  with up to microseconds (6 digits) precision. Along with providing fractional second precision, the new implementation for temporals is disk efficient.

What is an “Old Temporal”?

MySQL 8.0: ひらがなカタカナを判別する日本語用Collation

以前の記事では、MySQL 8.0.1で導入された新しい 日本語のutf8bm4のCollation(文字照合順)について ご紹介しました。このcollation (utf8mb4_ja_0900_as_cs) は、CLDR 30で定義されたアクセント記号(清音濁音半濁音)ならびに大文字小文字(拗音促音など)を判別する実装となっています。

今日ご紹介するのはひらがなカタカナを判別できる新しい「かなセンシティブ」なCollation utf8mb4_ja_0900_as_cs_ksです。 …

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MySQL8.0: 日本語のutf8bm4のCollation(文字照合順)

MySQL 8.0.1では、utf8mb4の大文字小文字およびアクセント記号付きの文字を判別するas_cs collationに加えて、日本語用のCollation(文字照合順)を追加しました。


日本語に関する文字照合およびソートのルールは複雑です。日本語ではひらがな、カタカナ、漢字、アルファベット(ラテン文字)を混在させて利用しています。さらに、全角と半角が存在する文字もあります。では、‘あ’, ‘ア’, ‘a’, ‘ア’はどのようにソートされるのでしょうか?

Unicode照合アルゴリズム(UCA / Unicode Collation …

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MySQL 8.0: Kana-sensitive collation for Japanese

In my previous post, I wrote about the new Japanese collation for utf8mb4 introduced in MySQL 8.0.1! This collation (utf8mb4_ja_0900_as_cs) implements accent / case sensitivity for Japanese as defined by CLDR 30.

Today, I am writing about our new utf8mb4_ja_0900_as_cs_ks collation which includes support for kana sensitivity.…

Debugging Character Set Issues by Example

In a world moving towards Unicode and UTF-8, a lot of applications still use some one-byte character set. And since one-byte characters usually accepts any byte in the range 0x00-0xFF it often works well to store and retrieve any data in such character strings, e.g.…

MySQL 8.0: When to use utf8mb3 over utf8mb4?

Long time MySQL users will recognize that there are two varieties of utf8 support in MySQL; utf8mb3 and utf8mb4.  Let me dig a little bit deeper in explaining the history between the two:

  • MySQL 4.1 (2004) was the first version to support character sets and collations.

MySQL 8.0 Collations: Migrating from older collations

From MySQL 8.0, utf8mb4 is the default character set, and the default collation for utf8mb4 is utf8mb4_0900_ai_ci. MySQL 8.0 is also coming with a whole new set of Unicode collations for the utf8mb4 character set.

This will allow use of the complete Unicode 9.0.0 character set in MySQL, and for new applications this is great news.…

MySQL 8.0.1: Accent and case sensitive collations for utf8mb4

In MySQL 8.0 we have been working to improve our support for utf8 as we make the transition to switch it to the default character set.  For more details see our earlier posts:

In today’s post I wanted to describe the improvements to support accent and case sensitive collations.…

New collations in MySQL 8.0.0

Since MySQL 5.5, MySQL has supported the utf8mb4 character set.  With the character-set defining the repertoire of characters that can be stored (utf8mb4 can present Unicode characters from U+0000 to U+10FFFF), a collation defines how sorting order and comparisons should behave.…

Upgrading JSON data stored in TEXT columns

One of the more frequently asked questions with MySQL 5.7 is “How can I upgrade my JSON data from using TEXT in an earlier version of MySQL to use the native JSON data type?”. Today I wanted to show an example of how to do so, using sample data from SF OpenData.…

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