gianm commented on a change in pull request #11550:
URL: https://github.com/apache/druid/pull/11550#discussion_r735042259
##########
File path: docs/querying/sql.md
##########
@@ -1123,20 +1123,23 @@ Segments table provides details on all Druid segments,
whether they are publishe
|version|STRING|Version string (generally an ISO8601 timestamp corresponding
to when the segment set was first started). Higher version means the more
recently created segment. Version comparing is based on string comparison.|
|partition_num|LONG|Partition number (an integer, unique within a
datasource+interval+version; may not necessarily be contiguous)|
|num_replicas|LONG|Number of replicas of this segment currently being served|
-|num_rows|LONG|Number of rows in current segment, this value could be null if
unknown to Broker at query time|
-|is_published|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 represents this segment has been published to the metadata store with
`used=1`. See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_available|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is currently being served by any process(Historical or
realtime). See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_realtime|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is _only_ served by realtime tasks, and 0 if any
historical process is serving this segment.|
-|is_overshadowed|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is published and is _fully_ overshadowed by some other
published segments. Currently, is_overshadowed is always false for unpublished
segments, although this may change in the future. You can filter for segments
that "should be published" by filtering for `is_published = 1 AND
is_overshadowed = 0`. Segments can briefly be both published and overshadowed
if they were recently replaced, but have not been unpublished yet. See the
[Architecture page](../design/architecture.md#segment-lifecycle) for more
details.|
+|num_rows|LONG|Number of rows in this segment. This field is updated in the
background and cached on the Broker. It may be null if the Broker has not
gathered a row count for this segment yet. It may not match the result of
`count(*)` queries on realtime data, because the cached value on the Broker may
be out of date, and because different replicas of realtime segments may not be
in sync with each other. Once a segment is published, its row count will settle
and stop changing.|
Review comment:
There's a little bit of delay between when a segment is published and
when num_rows becomes fully accurate, because it's fetched via doing a query to
a data server, rather than appearing in the published segment descriptor. I
updated the wording to the following, which is hopefully more clear:
> Number of rows in this segment, or zero if the number of rows is not known.
>
> This row count is gathered by the Broker in the background. It will be
zero if the Broker has not gathered a row count for this segment yet. For
segments ingested from streams, the reported row count may lag behind the
result of a `count(*)` query because the cached `num_rows` on the Broker may be
out of date. This will settle shortly after new rows stop being written to that
particular segment.
(I also changed "null" to "zero" because that's what it actually is.)
##########
File path: docs/querying/sql.md
##########
@@ -1123,20 +1123,23 @@ Segments table provides details on all Druid segments,
whether they are publishe
|version|STRING|Version string (generally an ISO8601 timestamp corresponding
to when the segment set was first started). Higher version means the more
recently created segment. Version comparing is based on string comparison.|
|partition_num|LONG|Partition number (an integer, unique within a
datasource+interval+version; may not necessarily be contiguous)|
|num_replicas|LONG|Number of replicas of this segment currently being served|
-|num_rows|LONG|Number of rows in current segment, this value could be null if
unknown to Broker at query time|
-|is_published|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 represents this segment has been published to the metadata store with
`used=1`. See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_available|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is currently being served by any process(Historical or
realtime). See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_realtime|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is _only_ served by realtime tasks, and 0 if any
historical process is serving this segment.|
-|is_overshadowed|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is published and is _fully_ overshadowed by some other
published segments. Currently, is_overshadowed is always false for unpublished
segments, although this may change in the future. You can filter for segments
that "should be published" by filtering for `is_published = 1 AND
is_overshadowed = 0`. Segments can briefly be both published and overshadowed
if they were recently replaced, but have not been unpublished yet. See the
[Architecture page](../design/architecture.md#segment-lifecycle) for more
details.|
+|num_rows|LONG|Number of rows in this segment. This field is updated in the
background and cached on the Broker. It may be null if the Broker has not
gathered a row count for this segment yet. It may not match the result of
`count(*)` queries on realtime data, because the cached value on the Broker may
be out of date, and because different replicas of realtime segments may not be
in sync with each other. Once a segment is published, its row count will settle
and stop changing.|
+|is_active|LONG|Boolean represented as long type where 1 = true, 0 = false.
True for segments that are either available and queryable, or _should be_
available and querayble. Equivalent to `(is_published = 1 AND is_overshadowed =
0) OR is_realtime = 1`.|
Review comment:
The context with the "should be" is that everything with regard to
ingestion and segment availability happens in the background and is
asynchronous. So some segments maybe should be available, but aren't right now,
and the system will work to make them available. Some others maybe are
available, but shouldn't be (because they were dropped or replaced), and the
system will work to make them unavailable.
I changed the wording to hopefully be more clear:
> True for segments that represent the latest state of a datasource.
>
> Equivalent to `(is_published = 1 AND is_overshadowed = 0) OR is_realtime =
1`. In steady state, when no ingestions or data management operations are
happening, `is_active` will be equivalent to `is_available`. However, they may
differ from each other when ingestions or data management operations have
executed recently. In these cases, Druid will load and unload segments
appropriately to bring actual availability in line with the expected state
given by `is_active`.
##########
File path: docs/querying/sql.md
##########
@@ -1123,20 +1123,23 @@ Segments table provides details on all Druid segments,
whether they are publishe
|version|STRING|Version string (generally an ISO8601 timestamp corresponding
to when the segment set was first started). Higher version means the more
recently created segment. Version comparing is based on string comparison.|
|partition_num|LONG|Partition number (an integer, unique within a
datasource+interval+version; may not necessarily be contiguous)|
|num_replicas|LONG|Number of replicas of this segment currently being served|
-|num_rows|LONG|Number of rows in current segment, this value could be null if
unknown to Broker at query time|
-|is_published|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 represents this segment has been published to the metadata store with
`used=1`. See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_available|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is currently being served by any process(Historical or
realtime). See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_realtime|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is _only_ served by realtime tasks, and 0 if any
historical process is serving this segment.|
-|is_overshadowed|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is published and is _fully_ overshadowed by some other
published segments. Currently, is_overshadowed is always false for unpublished
segments, although this may change in the future. You can filter for segments
that "should be published" by filtering for `is_published = 1 AND
is_overshadowed = 0`. Segments can briefly be both published and overshadowed
if they were recently replaced, but have not been unpublished yet. See the
[Architecture page](../design/architecture.md#segment-lifecycle) for more
details.|
+|num_rows|LONG|Number of rows in this segment. This field is updated in the
background and cached on the Broker. It may be null if the Broker has not
gathered a row count for this segment yet. It may not match the result of
`count(*)` queries on realtime data, because the cached value on the Broker may
be out of date, and because different replicas of realtime segments may not be
in sync with each other. Once a segment is published, its row count will settle
and stop changing.|
+|is_active|LONG|Boolean represented as long type where 1 = true, 0 = false.
True for segments that are either available and queryable, or _should be_
available and querayble. Equivalent to `(is_published = 1 AND is_overshadowed =
0) OR is_realtime = 1`.|
+|is_published|LONG|Boolean represented as long type where 1 = true, 0 = false.
1 represents this segment has been published to the metadata store with
`used=1`. See the [segment lifecycle
documentation](../design/architecture.md#segment-lifecycle) for more details.|
Review comment:
Yes.
##########
File path: docs/querying/sql.md
##########
@@ -1123,20 +1123,23 @@ Segments table provides details on all Druid segments,
whether they are publishe
|version|STRING|Version string (generally an ISO8601 timestamp corresponding
to when the segment set was first started). Higher version means the more
recently created segment. Version comparing is based on string comparison.|
|partition_num|LONG|Partition number (an integer, unique within a
datasource+interval+version; may not necessarily be contiguous)|
|num_replicas|LONG|Number of replicas of this segment currently being served|
-|num_rows|LONG|Number of rows in current segment, this value could be null if
unknown to Broker at query time|
-|is_published|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 represents this segment has been published to the metadata store with
`used=1`. See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_available|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is currently being served by any process(Historical or
realtime). See the [Architecture
page](../design/architecture.md#segment-lifecycle) for more details.|
-|is_realtime|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is _only_ served by realtime tasks, and 0 if any
historical process is serving this segment.|
-|is_overshadowed|LONG|Boolean is represented as long type where 1 = true, 0 =
false. 1 if this segment is published and is _fully_ overshadowed by some other
published segments. Currently, is_overshadowed is always false for unpublished
segments, although this may change in the future. You can filter for segments
that "should be published" by filtering for `is_published = 1 AND
is_overshadowed = 0`. Segments can briefly be both published and overshadowed
if they were recently replaced, but have not been unpublished yet. See the
[Architecture page](../design/architecture.md#segment-lifecycle) for more
details.|
+|num_rows|LONG|Number of rows in this segment. This field is updated in the
background and cached on the Broker. It may be null if the Broker has not
gathered a row count for this segment yet. It may not match the result of
`count(*)` queries on realtime data, because the cached value on the Broker may
be out of date, and because different replicas of realtime segments may not be
in sync with each other. Once a segment is published, its row count will settle
and stop changing.|
+|is_active|LONG|Boolean represented as long type where 1 = true, 0 = false.
True for segments that are either available and queryable, or _should be_
available and querayble. Equivalent to `(is_published = 1 AND is_overshadowed =
0) OR is_realtime = 1`.|
+|is_published|LONG|Boolean represented as long type where 1 = true, 0 = false.
1 represents this segment has been published to the metadata store with
`used=1`. See the [segment lifecycle
documentation](../design/architecture.md#segment-lifecycle) for more details.|
+|is_available|LONG|Boolean represented as long type where 1 = true, 0 = false.
1 if this segment is currently being served by any process(Historical or
realtime). See the [segment lifecycle
documentation](../design/architecture.md#segment-lifecycle) for more details.|
+|is_realtime|LONG|Boolean represented as long type where 1 = true, 0 = false.
1 if this segment is _only_ served by realtime tasks, and 0 if any historical
process is serving this segment.|
+|is_overshadowed|LONG|Boolean represented as long type where 1 = true, 0 =
false. 1 if this segment is published and is _fully_ overshadowed by some other
published segments. Currently, is_overshadowed is always 0 for unpublished
segments, although this may change in the future. You can filter for segments
that "should be published" by filtering for `is_published = 1 AND
is_overshadowed = 0`. Segments can briefly be both published and overshadowed
if they were recently replaced, but have not been unpublished yet. See the
[segment lifecycle documentation](../design/architecture.md#segment-lifecycle)
for more details.|
Review comment:
Thanks, fixed.
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