rocksdb/docs/_posts/2015-02-24-reading-rocksdb-options-from-a-file.markdown
2016-10-04 14:20:26 -07:00

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---
title: Reading RocksDB options from a file
layout: post
author: lgalanis
category: blog
redirect_from:
- /blog/1883/reading-rocksdb-options-from-a-file/
---
RocksDB options can be provided using a file or any string to RocksDB. The format is straightforward: `write_buffer_size=1024;max_write_buffer_number=2`. Any whitespace around `=` and `;` is OK. Moreover, options can be nested as necessary. For example `BlockBasedTableOptions` can be nested as follows: `write_buffer_size=1024; max_write_buffer_number=2; block_based_table_factory={block_size=4k};`. Similarly any white space around `{` or `}` is ok. Here is what it looks like in code:
<!--truncate-->
```c++
#include <string>
#include "rocksdb/db.h"
#include "rocksdb/table.h"
#include "rocksdb/utilities/convenience.h"
using namespace rocksdb;
int main(int argc, char** argv) {
DB *db;
Options opt;
std::string options_string =
"create_if_missing=true;max_open_files=1000;"
"block_based_table_factory={block_size=4096}";
Status s = GetDBOptionsFromString(opt, options_string, &opt);
s = DB::Open(opt, "/tmp/mydb_rocks", &db);
// use db
delete db;
}
```
Using `GetDBOptionsFromString` is a convenient way of changing options for your RocksDB application without needing to resort to recompilation or tedious command line parsing.