Japanese, Chinese and other non-ASCII searching not quite working

[matrixbot]

This issue has been migrated from #901.

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Hi - on a synapse homeserver running on postgresql 9.4, and connecting via vector, I'm having trouble searching Japanese.

If I enter:

バッタと鈴虫

(grasshopper and cricket)
I get a search hit when I search バッタ but, not when I search 鈴虫.

It appears that the beginning of a post is ok, but, anywhere in the middle of the post is not searchable. I tried this on my own homeserver, and on the main matrix homeserver. Same result. Kent on the main forum also reproduced.

Is there a possibility to search using regex?

[code-gal]

Here is a temporary solution for Chinese：给 Matrix Synapse 添加中文搜索

[fofwisdom]

Korean is also an issue. CJK attaches an postpositions to the end of a word, so searching for a phrase is pointless. For Asians, Synapse seems useless for work or community.