MVStore.Builder

Read the configuration from a string.

Creates new instance of MVStore.Builder.

Set the size of the write buffer, in KB disk space (for file-based stores). Unless auto-commit is disabled, changes are automatically saved if there are more than this amount of changes.

The default is 1024 KB.

When the value is set to 0 or lower, data is not automatically stored.

Disable auto-commit, by setting the auto-commit delay and auto-commit buffer size to 0.

Set the auto-compact target fill rate. If the average fill rate (the percentage of the storage space that contains active data) of the chunks is lower, then the chunks with a low fill rate are re-written. Also, if the percentage of empty space between chunks is higher than this value, then chunks at the end of the file are moved. Compaction stops if the target fill rate is reached.

The default value is 40 (40%). The value 0 disables auto-compacting.

Set the listener to be used for exceptions that occur when writing in the background thread.

Set the read cache concurrency. The default is 16, meaning 16 segments are used.

Set the read cache size in MB. The default is 16 MB.

Compress data before writing using the LZF algorithm. This will save about 50% of the disk space, but will slow down read and write operations slightly.

This setting only affects writes; it is not necessary to enable compression when reading, even if compression was enabled when writing.

Compress data before writing using the Deflate algorithm. This will save more disk space, but will slow down read and write operations quite a bit.

This setting only affects writes; it is not necessary to enable compression when reading, even if compression was enabled when writing.

Encrypt / decrypt the file using the given password. This method has no effect for in-memory stores. The password is passed as a char array so that it can be cleared as soon as possible. Please note there is still a small risk that password stays in memory (due to Java garbage collection). Also, the hashed encryption key is kept in memory as long as the file is open.

Use the following file name. If the file does not exist, it is automatically created. The parent directory already must exist.

Use the provided file store instead of the default one.

File stores passed in this way need to be open. They are not closed when closing the store.

Please note that any kind of store (including an off-heap store) is considered a "persistence", while an "in-memory store" means objects are not persisted and fully kept in the JVM heap.

Open the store.

Set the amount of memory a page should contain at most, in bytes, before it is split. The default is 16 KB for persistent stores and 4 KB for in-memory stores. This is not a limit in the page size, as pages with one entry can get larger. It is just the point where pages that contain more than one entry are split.

Open the file in read-only mode. In this case, a shared lock will be acquired to ensure the file is not concurrently opened in write mode.

If this option is not used, the file is locked exclusively.

Please note a store may only be opened once in every JVM (no matter whether it is opened in read-only or read-write mode), because each file may be locked only once in a process.