最大限度.宽行的大小? [英] Max. size of wide rows?
问题描述
理论上,Cassandra 允许在宽行中最多包含 20 亿列.
Theoretically, Cassandra allows up to 2 billion columns in a wide row.
我听说实际上高达 50.000 cols/50 MB 就可以了;50.000-100.000 cols/100 MB 可以,但需要一些调整;并且每行的列数不应超过 100.000/100 MB.原因是这会给堆带来压力.
I have heard that in reality up to 50.000 cols/50 MB are fine; 50.000-100.000 cols/100 MB are OK but require some tuning; and that one should never go above 100.000/100 MB columns per row. The reason being that this will put pressure on the heap.
这有什么道理吗?
推荐答案
在 Cassandra 中,最大单元格数单个分区中(行 x 列)为 20 亿.
In Cassandra, the maximum number of cells (rows x columns) in a single partition is 2 billion.
此外,单个列值可能不会大于 2GB,但实际上,MB 的个位数"是更合理的限制,因为没有流式传输或随机访问 blob 值.
Additionally, a single column value may not be larger than 2GB, but in practice, "single digits of MB" is a more reasonable limit, since there is no streaming or random access of blob values.
大于 100Mb 的分区会对堆造成巨大压力.
Partitions greater than 100Mb can cause significant pressure on the heap.
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