Release notes header 2.15.0

.unreleased/RELEASE_NOTES_HEADER.md.j2

@@ -0,0 +1,20 @@
+## {{ release_current }} ({{ release_date }})
+
+This release contains performance improvements and bug fixes since 
+the {{ release_previous }} release. We recommend that you upgrade at the next
+available opportunity.
+
+In addition, it includes these noteworthy features:
+* Support `time_bucket` with `origin` and/or `offset` on Continuous Aggregate
+* Compression improvements:
+  - Improve expression pushdown
+  - Add minmax sparse indexes when compressing columns with btree indexes
+  - Make compression use the defaults functions
+* Vectorize filters in WHERE clause that contain text equality operators and LIKE expressions
+
+**Deprecation warning**
+* Starting on this release will not be possible to create Continuous Aggregate using `time_bucket_ng` anymore and it will be completely removed on the upcoming releases.
+* Recommend users to [migrate their old Continuous Aggregate format to the new one](https://docs.timescale.com/use-timescale/latest/continuous-aggregates/migrate/) because it support will be completely removed in next releases prevent them to migrate.
+* PG13 deprecation??
+
+**For on-premise users and this release only**, you will need to run [this SQL script](https://github.com/timescale/timescaledb-extras/blob/master/utils/2.15.X-fix_hypertable_foreign_keys.sql) after running `ALTER EXTENSION`. More details can be found in the pull request [#6786](https://github.com/timescale/timescaledb/pull/6797).

.unreleased/pr_6621

@@ -1,2 +1,2 @@
 Fixes: #6621 Remove metadata when dropping chunks
-Thanks: @ndjzurawsk For reporting error when dropping chunks
+Thanks: @djzurawsk For reporting error when dropping chunks

scripts/merge_changelogs.sh

@@ -4,14 +4,14 @@
 # This script build a CHANGELOG.md entry for a new release
 #
 
-RELEASE_NOTES_TEMPLATE='.unreleased/RELEASE_NOTES.md.j2'
+RELEASE_NOTES_HEADER_TEMPLATE='.unreleased/RELEASE_NOTES_HEADER.md.j2'
 
 echo_changelog() {
     echo "${1}"
     # skip the template and release notes files
     grep -i "${2}" .unreleased/* | \
         grep -v '.unreleased/template.*' | \
-        grep -v "${RELEASE_NOTES_TEMPLATE}" | \
+        grep -v "${RELEASE_NOTES_HEADER_TEMPLATE}" | \
         cut -d: -f3- | sort | uniq | sed -e 's/^[[:space:]]*//' -e 's/^/* /'
     echo
 }
@@ -28,12 +28,12 @@ RELEASE_DATE=$(date +"%Y-%m-%d")
 # To install jinja template client:
 #   $ pip install jinja-cli
 #
-if [ -f "${RELEASE_NOTES_TEMPLATE}" ];
+if [ -f "${RELEASE_NOTES_HEADER_TEMPLATE}" ];
 then
     jinja \
         -D release_current "${RELEASE_CURRENT}" \
         -D release_previous "${RELEASE_PREVIOUS}" \
-        -D release_date "${RELEASE_DATE}" ${RELEASE_NOTES_TEMPLATE}
+        -D release_date "${RELEASE_DATE}" ${RELEASE_NOTES_HEADER_TEMPLATE}
     echo
 fi