#require no-reposimplestore

  $ cat >> $HGRCPATH << EOF

  > [extensions]

  > share =

  > EOF

store and revlogv1 are required in source

  $ hg --config format.usestore=false init no-store

  $ hg -R no-store debugupgraderepo

  abort: cannot upgrade repository; requirement missing: store

  [255]

  $ hg init no-revlogv1

  $ cat > no-revlogv1/.hg/requires << EOF

  > dotencode

  > fncache

  > generaldelta

  > store

  > EOF

  $ hg -R no-revlogv1 debugupgraderepo

  abort: cannot upgrade repository; requirement missing: revlogv1

  [255]

Cannot upgrade shared repositories

  $ hg init share-parent

  $ hg -q share share-parent share-child

  $ hg -R share-child debugupgraderepo

  abort: cannot upgrade repository; unsupported source requirement: shared

  [255]

Do not yet support upgrading treemanifest repos

  $ hg --config experimental.treemanifest=true init treemanifest

  $ hg -R treemanifest debugupgraderepo

  abort: cannot upgrade repository; unsupported source requirement: treemanifest

  [255]

Cannot add treemanifest requirement during upgrade

  $ hg init disallowaddedreq

  $ hg -R disallowaddedreq --config experimental.treemanifest=true debugupgraderepo

  abort: cannot upgrade repository; do not support adding requirement: treemanifest

  [255]

An upgrade of a repository created with recommended settings only suggests optimizations

  $ hg init empty

  $ cd empty

  $ hg debugformat

  format-variant    repo

  fncache:           yes

  dotencode:         yes

  generaldelta:      yes

  sparserevlog:      yes

  sidedata:           no

  copies-sdc:         no

  plain-cl-delta:    yes

  compression:       zlib

  compression-level: default

  $ hg debugformat --verbose

  format-variant    repo config default

  fncache:           yes    yes     yes

  dotencode:         yes    yes     yes

  generaldelta:      yes    yes     yes

  sparserevlog:      yes    yes     yes

  sidedata:           no     no      no

  copies-sdc:         no     no      no

  plain-cl-delta:    yes    yes     yes

  compression:       zlib   zlib    zlib

  compression-level: default default default

  $ hg debugformat --verbose --config format.usefncache=no

  format-variant    repo config default

  fncache:           yes     no     yes

  dotencode:         yes     no     yes

  generaldelta:      yes    yes     yes

  sparserevlog:      yes    yes     yes

  sidedata:           no     no      no

  copies-sdc:         no     no      no

  plain-cl-delta:    yes    yes     yes

  compression:       zlib   zlib    zlib

  compression-level: default default default

  $ hg debugformat --verbose --config format.usefncache=no --color=debug

  format-variant    repo config default

  [formatvariant.name.mismatchconfig|fncache:          ][formatvariant.repo.mismatchconfig| yes][formatvariant.config.special|     no][formatvariant.default|     yes]

  [formatvariant.name.mismatchconfig|dotencode:        ][formatvariant.repo.mismatchconfig| yes][formatvariant.config.special|     no][formatvariant.default|     yes]

  [formatvariant.name.uptodate|generaldelta:     ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|sparserevlog:     ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|sidedata:         ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]

  [formatvariant.name.uptodate|copies-sdc:       ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]

  [formatvariant.name.uptodate|plain-cl-delta:   ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|compression:      ][formatvariant.repo.uptodate| zlib][formatvariant.config.default|   zlib][formatvariant.default|    zlib]

  [formatvariant.name.uptodate|compression-level:][formatvariant.repo.uptodate| default][formatvariant.config.default| default][formatvariant.default| default]

  $ hg debugformat -Tjson

  [

   {

    "config": true,

    "default": true,

    "name": "fncache",

    "repo": true

   },

   {

    "config": true,

    "default": true,

    "name": "dotencode",

    "repo": true

   },

   {

    "config": true,

    "default": true,

    "name": "generaldelta",

    "repo": true

   },

   {

    "config": true,

    "default": true,

    "name": "sparserevlog",

    "repo": true

   },

   {

    "config": false,

    "default": false,

    "name": "sidedata",

    "repo": false

   },

   {

    "config": false,

    "default": false,

    "name": "copies-sdc",

    "repo": false

   },

   {

    "config": true,

    "default": true,

    "name": "plain-cl-delta",

    "repo": true

   },

   {

    "config": "zlib",

    "default": "zlib",

    "name": "compression",

    "repo": "zlib"

   },

   {

    "config": "default",

    "default": "default",

    "name": "compression-level",

    "repo": "default"

   }

  ]

  $ hg debugupgraderepo

  (no feature deficiencies found in existing repository)

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store

  sidedata

     Allows storage of extra data alongside a revision.

  copies-sdc

     Allows to use more efficient algorithm to deal with copy tracing.

  additional optimizations are available by specifying "--optimize <name>":

  re-delta-parent

     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower

  re-delta-multibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  re-delta-all

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

  re-delta-fulladd

     every revision will be re-added as if it was new content. It will go through the full storage mechanism giving extensions a chance to process it (eg. lfs). This is similar to "re-delta-all" but even slower since more logic is involved.

--optimize can be used to add optimizations

  $ hg debugupgrade --optimize redeltaparent

  (no feature deficiencies found in existing repository)

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store

  sidedata

     Allows storage of extra data alongside a revision.

  copies-sdc

     Allows to use more efficient algorithm to deal with copy tracing.

  re-delta-parent

     deltas within internal storage will choose a new base revision if needed

  additional optimizations are available by specifying "--optimize <name>":

  re-delta-multibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  re-delta-all

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

  re-delta-fulladd

     every revision will be re-added as if it was new content. It will go through the full storage mechanism giving extensions a chance to process it (eg. lfs). This is similar to "re-delta-all" but even slower since more logic is involved.

modern form of the option

  $ hg debugupgrade --optimize re-delta-parent

  (no feature deficiencies found in existing repository)

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store

  sidedata

     Allows storage of extra data alongside a revision.

  copies-sdc

     Allows to use more efficient algorithm to deal with copy tracing.

  re-delta-parent

     deltas within internal storage will choose a new base revision if needed

  additional optimizations are available by specifying "--optimize <name>":

  re-delta-multibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  re-delta-all

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

  re-delta-fulladd

     every revision will be re-added as if it was new content. It will go through the full storage mechanism giving extensions a chance to process it (eg. lfs). This is similar to "re-delta-all" but even slower since more logic is involved.

unknown optimization:

  $ hg debugupgrade --optimize foobar

  abort: unknown optimization action requested: foobar

  (run without arguments to see valid optimizations)

  [255]

Various sub-optimal detections work

  $ cat > .hg/requires << EOF

  > revlogv1

  > store

  > EOF

  $ hg debugformat

  format-variant    repo

  fncache:            no

  dotencode:          no

  generaldelta:       no

  sparserevlog:       no

  sidedata:           no

  copies-sdc:         no

  plain-cl-delta:    yes

  compression:       zlib

  compression-level: default

  $ hg debugformat --verbose

  format-variant    repo config default

  fncache:            no    yes     yes

  dotencode:          no    yes     yes

  generaldelta:       no    yes     yes

  sparserevlog:       no    yes     yes

  sidedata:           no     no      no

  copies-sdc:         no     no      no

  plain-cl-delta:    yes    yes     yes

  compression:       zlib   zlib    zlib

  compression-level: default default default

  $ hg debugformat --verbose --config format.usegeneraldelta=no

  format-variant    repo config default

  fncache:            no    yes     yes

  dotencode:          no    yes     yes

  generaldelta:       no     no     yes

  sparserevlog:       no     no     yes

  sidedata:           no     no      no

  copies-sdc:         no     no      no

  plain-cl-delta:    yes    yes     yes

  compression:       zlib   zlib    zlib

  compression-level: default default default

  $ hg debugformat --verbose --config format.usegeneraldelta=no --color=debug

  format-variant    repo config default

  [formatvariant.name.mismatchconfig|fncache:          ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.mismatchconfig|dotencode:        ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.mismatchdefault|generaldelta:     ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]

  [formatvariant.name.mismatchdefault|sparserevlog:     ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]

  [formatvariant.name.uptodate|sidedata:         ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]

  [formatvariant.name.uptodate|copies-sdc:       ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]

  [formatvariant.name.uptodate|plain-cl-delta:   ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|compression:      ][formatvariant.repo.uptodate| zlib][formatvariant.config.default|   zlib][formatvariant.default|    zlib]

  [formatvariant.name.uptodate|compression-level:][formatvariant.repo.uptodate| default][formatvariant.config.default| default][formatvariant.default| default]

  $ hg debugupgraderepo

  repository lacks features recommended by current config options:

  fncache

     long and reserved filenames may not work correctly; repository performance is sub-optimal

  dotencode

     storage of filenames beginning with a period or space may not work correctly

  generaldelta

     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower

  sparserevlog

     in order to limit disk reading and memory usage on older version, the span of a delta chain from its root to its end is limited, whatever the relevant data in this span. This can severly limit Mercurial ability to build good chain of delta resulting is much more storage space being taken and limit reusability of on disk delta during exchange.

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: revlogv1, store

     added: dotencode, fncache, generaldelta, sparserevlog

  fncache

     repository will be more resilient to storing certain paths and performance of certain operations should be improved

  dotencode

     repository will be better able to store files beginning with a space or period

  generaldelta

     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster