Wrong behavior of outputs.sql.convert unsigned setting

[crabvk]

Relevant telegraf.conf

[[outputs.sql]]
  driver = "clickhouse"
  data_source_name = "tcp://example.com:9000?username=user&password=pass&database=db"
  table_template = "CREATE TABLE {TABLE}({COLUMNS}) ENGINE = MergeTree() ORDER by timestamp"
  [outputs.sql.convert]
    integer = "Int64"
    real = "Float64"
    text = "String"
    timestamp = "DateTime"
    defaultvalue = "String"
    unsigned = "UInt64"
    bool = "Uint8"

Logs from Telegraf

2022-02-14T06:01:11Z E! [agent] Error writing to outputs.sql: code: 62, message: Syntax error: failed at position 72 ('UInt64'): UInt64,"inactive" Int64 UInt64,"vmalloc_chunk" Int64 UInt64,"sreclaimable" Int64 UInt64,"swap_cached" Int64 UInt64,"used" Int64 UInt64,"huge_pages_free" Int64 U. Expected one of: DEFAULT, MATERIALIZED, ALIAS, NOT, NULL, COMMENT, CODEC, TTL, token, Comma, ClosingRoundBracket

System info

Telegraf built from master branch (with #9671 PR merged), ArchLinux 5.16.8

Steps to reproduce

1. Use telegraf config above
2. Run telegraf to collect metrics to ClickHouse
3. Got the error

Expected behavior

No errors

Actual behavior

This line causes the error, because when value type is uint64 the datatype becomes Int64 UInt64.

Additional info

Setting unsigned is exceptional, in fact it behaves more like unsigned_suffix now. To fix the issue the code should be

datatype = p.Convert.Unsigned

as with other data type settings, and default config for setting unsigned should be changed to

[outputs.sql.convert]
    unsigned = "INT UNSIGNED"

instead of

[outputs.sql.convert]
    unsigned = "UNSIGNED"

UNSIGNED is not a type on its own, it is a suffix.

[powersj]

Hi @crabvk,

Would you take a look at this PR and try one of the artifacts that are attached (once tests are built).

Thanks!

[powersj]

Thank you for confirming in the PR that this fixes things. I am going to re-open this since my PR isn't merge quite yet :)