feat(outputs.postgresql): Add option to create time column with timezone

[srebhan]

• Updated associated README.md.
• Wrote appropriate unit tests.
• Pull request title or commits are in conventional commit format

resolves #13747
based on #13750

This PR adds the ability to switch the time-column to PostgeSQL's "timestamp with time zone" type allowing to issue queries with timezones. Please note, the timestamp is still always transmitted as UTC!

[srebhan]

@phemmer would love to get your review on this one too!

[jcpunk]

With my limited testing this seems to do what I'm looking for.

[phemmer]

@phemmer would love to get your review on this one too!

Seems fairly reasonable.
What I meant on the other PR regarding defaults was to put them here with the others so they're all in one place:

telegraf/plugins/outputs/postgresql/postgresql.go

Lines 73 to 85 in 879c42d

	p := &Postgresql{
	Schema: "public",
	TagTableSuffix: "_tag",
	TagCacheSize: 100000,
	Uint64Type: PgNumeric,
	CreateTemplates: []*sqltemplate.Template{{}},
	AddColumnTemplates: []*sqltemplate.Template{{}},
	TagTableCreateTemplates: []*sqltemplate.Template{{}},
	TagTableAddColumnTemplates: []*sqltemplate.Template{{}},
	RetryMaxBackoff: config.Duration(time.Second * 15),
	Logger: models.NewLogger("outputs", "postgresql", ""),
	LogLevel: "warn",
	}

But it's just personal preference. What you have is functionally fine.

One change I might suggest though is how to specify the type. Instead of a boolean, use a more generic "timestamp_type" field with a text value which can be "timestamptz" (or "timestamp with timezone" for the full name). This makes it more future proof, as it's possible in the future there might be some other data type, such as integer, which would require another parameter, and make everything rather messy.

Oh, and I think this change might be incomplete as it is. Just changing the column type to timezone doesn't serve much purpose. telegraf point timestamps don't contain timezone information. So you have to pull a timezone from somewhere. Where is this coming from?

[srebhan]

One change I might suggest though is how to specify the type. Instead of a boolean, use a more generic "timestamp_type" field with a text value which can be "timestamptz" (or "timestamp with timezone" for the full name). This makes it more future proof, as it's possible in the future there might be some other data type, such as integer, which would require another parameter, and make everything rather messy.

That is reasonable and I will do that.

Regarding the defaults for the column: I like to do it in Init() to also cover the case where the user set the option to an empty string (by accident) as this would likely cause all types of issues...

[jcpunk]

Let me know when the next test binary is posted and I can give it a shot.

[telegraf-tiger]

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Downloads for additional architectures and packages are available below.

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Artifact URLs

DEB	RPM	TAR GZ	ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

[jcpunk]

This is working as I'd expect for cases when my provided time string is unix_ms. Telegraf is setting that to UTC for me "somehow".