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https://issues.apache.org/jira/browse/IGNITE-19304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17731636#comment-17731636
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Andrey Mashenkov commented on IGNITE-19304:
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Creating index with duplicates columns looks like a typo.
The second and further mentions of the same column in index definition has no
affect on behaviour.
In general case, fixing a type by dropping useless columns may lead to
unexpected result.
E.g. for index on (col1, col2, col1) there are 2 possible ways to fix this that
lead to completely different results: index on (col1, col2) and index on (col2,
col2).
> Create index with the same column twice
> ---------------------------------------
>
> Key: IGNITE-19304
> URL: https://issues.apache.org/jira/browse/IGNITE-19304
> Project: Ignite
> Issue Type: Bug
> Components: sql
> Affects Versions: 3.0
> Reporter: Alexander Belyak
> Assignee: Andrey Mashenkov
> Priority: Minor
> Labels: ignite-3
> Fix For: 3.0.0-beta2
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Unable to create index with same column twice:
> {noformat}
> create table tindex(
> id int primary key,
> v1 int,
> v2 int);
> create index titest on tindex(v1,v1){noformat}
> error:
> {noformat}
> [Code: 0, SQL State: 50000] Exception while executing query [query=create
> index titest on tindex(v1,v1)]. Error message:IGN-CMN-65535
> TraceId:203a2c0c-fbf1-4143-aa47-50c97223ad84 Named List element with key "V1"
> already exists{noformat}
> But documentation
> [https://ignite.apache.org/docs/3.0.0-beta/sql-reference/ddl#create-index] do
> not block it. Postgres allow to execute such DDL too.
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