Use -Zmacro-stats to optimize macros and reduce compile time

[Nutomic]

Backend

PostgreSQL, MySQL, SQLite, Others

What do you want to add to diesel?

On Rust nightly there is a new flag -Zmacro-stats which shows the amount of code generated by macros. Diesel uses a lot of macros so this could be helpful to remove unnecessary parts and make compilation faster. See this blog post for more details. Another post has details how this was used to optimize macros in Bevy.

For diesel it shows the following output (this is with 64-column-tables and some other features enabled):

$ RUSTFLAGS="-Zmacro-stats" cargo +nightly build
macro-stats ===================================================================================
macro-stats MACRO EXPANSION STATS: diesel
macro-stats Macro Name                         Uses      Lines  Avg Lines      Bytes  Avg Bytes
macro-stats -----------------------------------------------------------------------------------
macro-stats impl_sql_type!                    2_080    517_891      249.0 36_738_505   17_662.7
macro-stats tuple_impls!                          3    164_178   54_726.0  8_698_5132_899_504.3
macro-stats fake_variadic!                      960     44_857       46.7  2_564_126    2_671.0
macro-stats impl_copy_from_insertable_helper_for_values_clause!
macro-stats                                       1     52_752   52_752.0  2_496_3352_496_335.0
macro-stats impl_from_sql_row!                   64     37_476      585.6  1_867_608   29_181.4
macro-stats valid_ordering!                   1_608     15_736        9.8    690_635      429.5
macro-stats ::core::assert_eq!                2_081     18_729        9.0    654_915      314.7
macro-stats #[declare_sql_function]               7     12_860    1_837.1    549_237   78_462.4
macro-stats diesel_derives::__diesel_for_each_tuple!
macro-stats                                      10      7_851      785.1    509_309   50_930.9
macro-stats impl_positional_order_expr_for_all_tuples!
macro-stats                                       1      6_256    6_256.0    362_429  362_429.0
macro-stats on_conflict_tuples!                   1      7_625    7_625.0    355_454  355_454.0
macro-stats copy_target_for_columns!              1      4_051    4_051.0    253_947  253_947.0
macro-stats field_alias_mapper!                   1      4_143    4_143.0    226_803  226_803.0
macro-stats #[derive(diesel::sql_types::DieselNumericOps)]
macro-stats                                      85      4_484       52.8    215_538    2_535.7
macro-stats debug_assert_eq!                  2_081      6_243        3.0    199_176       95.7
macro-stats impl_eq_all!                         64      2_944       46.0    180_578    2_821.5
macro-stats impl_valid_grouping_for_tuple_of_columns!
macro-stats                                      64      2_558       40.0    151_570    2_368.3
macro-stats #[derive(Debug)]                    427      3_805        8.9    144_695      338.9
macro-stats #[derive(crate::sql_types::DieselNumericOps)]
macro-stats                                      59      3_068       52.0    143_998    2_440.6
macro-stats crate::__diesel_operator_body!       64      3_008       47.0    136_380    2_130.9
macro-stats #[derive(AsExpression)]              31      3_032       97.8    132_808    4_284.1
macro-stats #[derive(diesel::query_builder::QueryId)]
macro-stats                                     102      2_513       24.6    116_349    1_140.7
macro-stats #[derive(Clone)]                    403      3_493        8.7    112_098      278.2
macro-stats #[diesel_derives::__diesel_public_if]
macro-stats                                      72      2_003       27.8     86_365    1_199.5
macro-stats crate::__diesel_infix_operator!      86      1_246       14.5     83_723      973.5
macro-stats #[derive(QueryId)]                  142      2_078       14.6     79_182      557.6
macro-stats #[derive(ValidGrouping)]             94      1_771       18.8     74_860      796.4
macro-stats table!                                2      1_399      699.5     70_135   35_067.5
macro-stats #[derive(crate::query_builder::QueryId)]
macro-stats                                      60      1_156       19.3     49_705      828.4
macro-stats #[derive(Copy)]                     392      1_251        3.2     45_340      115.7
macro-stats #[derive(crate::expression::ValidGrouping)]
macro-stats                                      59      1_090       18.5     44_372      752.1
macro-stats crate::impl_selectable_expression!  131        706        5.4     38_690      295.3
macro-stats #[derive(DieselNumericOps)]          11        572       52.0     26_682    2_425.6
macro-stats impl_eq_all_for_all_tuples!           1        353      353.0     22_777   22_777.0
macro-stats multirange_as_expression!            60        420        7.0     18_976      316.3
macro-stats ::core::panic::unreachable_2021!    193        257        1.3     17_796       92.2
macro-stats #[derive(SqlType)]                   33        474       14.4     17_407      527.5
macro-stats ::bitflags::__impl_bitflags!          2        383      191.5     15_474    7_737.0
macro-stats #[derive(FromSqlRow)]                31        404       13.0     14_420      465.2
macro-stats ::core::panic::panic_2021!           64        320        5.0     13_568      212.0
macro-stats format!                              76        296        3.9     13_025      171.4
macro-stats ::bitflags::__bitflags_expr_safe_attrs!
macro-stats                                      48        369        7.7     11_296      235.3
macro-stats generic_numeric_expr_inner!          16        208       13.0     10_672      667.0
macro-stats #[derive(Default)]                   60        366        6.1     10_313      171.9
macro-stats ::bitflags::__impl_public_bitflags_consts!
macro-stats                                       1        218      218.0     10_226   10_226.0
macro-stats ::core::panic!                       64        128        2.0      9_792      153.0
macro-stats unreachable!                        193        193        1.0      9_698       50.2
macro-stats #[derive(PartialEq)]                 21        234       11.1      9_084      432.6
macro-stats ::core::const_format_args!           67        131        2.0      8_937      133.4
macro-stats ::bitflags::__impl_public_bitflags_ops!
macro-stats                                       2        208      104.0      8_692    4_346.0
macro-stats ::core::cfg!                      2_082      2_082        1.0      8_328        4.0
macro-stats ::bitflags::__impl_public_bitflags!   1        181      181.0      8_298    8_298.0
macro-stats #[derive(diesel_derives::AsExpression)]
macro-stats                                       2        179       89.5      8_056    4_028.0
macro-stats simple_clause!                       10        182       18.2      7_337      733.7
macro-stats range_as_expression!                 24        163        6.8      7_076      294.8
macro-stats crate::postfix_operator!             10         95        9.5      6_485      648.5
macro-stats ::alloc::__export::format_args!      76         78        1.0      5_747       75.6
macro-stats simple_frame_expr_with_bound!         5        143       28.6      5_569    1_113.8
macro-stats multirange_as_expressions!            6        111       18.5      5_326      887.7
macro-stats crate::__diesel_operator_to_sql!     58        159        2.7      5_195       89.6
macro-stats ::core::format_args!                 83         85        1.0      5_122       61.7
macro-stats crate::infix_operator!               29         88        3.0      5_111      176.2
macro-stats #[derive(Eq)]                        19        176        9.3      4_882      256.9
macro-stats ::bitflags::__bitflags_flag!         24        112        4.7      4_584      191.0
macro-stats numeric_operation!                    4        124       31.0      4_096    1_024.0
macro-stats type_name!                            1        104      104.0      3_989    3_989.0
macro-stats multirange_to_sql_nullable!           6         95       15.8      3_834      639.0
macro-stats infix_operator!                      36         66        1.8      3_481       96.7
macro-stats multirange_std_to_sql!                5         87       17.4      3_456      691.2
macro-stats simple_frame_expr!                    5         83       16.6      2_957      591.4
macro-stats casts_impl!                           1         52       52.0      2_939    2_939.0
macro-stats array_as_expression!                 10         63        6.3      2_758      275.8
macro-stats #[derive(Hash)]                       9         78        8.7      2_716      301.8
macro-stats ::bitflags::__impl_public_bitflags_iter!
macro-stats                                       2         58       29.0      2_598    1_299.0
macro-stats empty_clause!                         7         77       11.0      2_514      359.1
macro-stats #[derive(sql_types::DieselNumericOps)]
macro-stats                                       1         52       52.0      2_422    2_422.0
macro-stats ::bitflags::__impl_public_bitflags_forward!
macro-stats                                       1         45       45.0      2_201    2_201.0
macro-stats crate::joinable_inner!                4         40       10.0      2_201      550.2
macro-stats #[derive(PartialOrd)]                 7         63        9.0      2_160      308.6
macro-stats impl_downcast!                        4         54       13.5      2_100      525.0
macro-stats ::bitflags::__impl_internal_bitflags! 1         51       51.0      2_043    2_043.0
macro-stats postfix_operator!                    14         33        2.4      1_981      141.5
macro-stats range_to_sql_nullable!                6         48        8.0      1_946      324.3
macro-stats numeric_type!                         1         96       96.0      1_787    1_787.0
macro-stats operator_allowed!                     4         40       10.0      1_764      441.0
macro-stats #[derive(Ord)]                        7         53        7.6      1_634      233.4
macro-stats bitflags::bitflags!                   1         38       38.0      1_577    1_577.0
macro-stats write!                               18         23        1.3      1_503       83.5
macro-stats range_std_to_sql!                     5         40        8.0      1_471      294.2
macro-stats impl_selectable_expression!          15         27        1.8      1_278       85.2
macro-stats crate::__diesel_internal_backend_specific_allow_tables_to_appear_in_same_query!
macro-stats                                       1         22       22.0      1_267    1_267.0
macro-stats __diesel_infix_operator!              7         21        3.0      1_260      180.0
macro-stats multirange_has_sql_type!              6         36        6.0      1_143      190.5
macro-stats foldable_impls!                       1         28       28.0      1_063    1_063.0
macro-stats fallible_casts_impl!                  1         16       16.0        941      941.0
macro-stats generic_numeric_expr!                 4         16        4.0        828      207.0
macro-stats crate::prefix_operator!               1         12       12.0        777      777.0
macro-stats #[derive(Queryable)]                  1         20       20.0        730      730.0
macro-stats ::bitflags::__impl_external_bitflags! 1         21       21.0        696      696.0
macro-stats allow_tables_to_appear_in_same_query! 1          7        7.0        342      342.0
macro-stats ::std::panic::panic_2021!             3         10        3.3        339      113.0
macro-stats assert_eq!                            1          9        9.0        320      320.0
macro-stats matches!                              2          9        4.5        293      146.5
macro-stats joinable!                             1          4        4.0        239      239.0
macro-stats panic!                                3          3        1.0        211       70.3
macro-stats ::bitflags::__private::core::stringify!
macro-stats                                      16         16        1.0        144        9.0
macro-stats vec!                                  3          3        1.0        111       37.0
macro-stats ::bitflags::__declare_internal_bitflags!
macro-stats                                       1          3        3.0        110      110.0
macro-stats ::core::assert!                       1          3        3.0         95       95.0
macro-stats ::bitflags::__private::core::write!   1          2        2.0         89       89.0
macro-stats ::bitflags::__declare_public_bitflags!
macro-stats                                       1          1        1.0         76       76.0
macro-stats debug_assert!                         1          1        1.0         74       74.0
macro-stats prefix_operator!                      1          1        1.0         68       68.0
macro-stats downcast_rs::impl_downcast!           1          1        1.0         65       65.0
macro-stats unimplemented!                        1          1        1.0         43       43.0
macro-stats crate::allow_tables_to_appear_in_same_query!
macro-stats                                       1          1        1.0          0        0.0
macro-stats ::bitflags::bitflags!                 1          1        1.0          0        0.0
macro-stats ::bitflags::__impl_external_bitflags_bytemuck!
macro-stats                                       1          1        1.0          0        0.0
macro-stats ::bitflags::__impl_external_bitflags_arbitrary!
macro-stats                                       1          1        1.0          0        0.0
macro-stats ::bitflags::__impl_external_bitflags_serde!
macro-stats                                       1          1        1.0          0        0.0
macro-stats ===================================================================================

Implementation notes

I dont have any experience writing macros so no idea. The blog posts linked above may help.

Additional details

No response

Checklist

• I have already looked over the issue tracker and the discussion forum for similar possible closed issues.

[weiznich]

I'm happy to accept actual improvements or suggestions what to change here. Otherwise I'm well aware of these tools and already use them so this post as it is does not add any new information for me.

More generally written: I do not think that order of magnitude improvements in terms of compile times with 64 or 128 columns-tables enabled are possible without significant language changes like variadic generics.

[weiznich]

To give some more specific examples: The impl_sql_type macro is listed as the macro that generates the largest amount of code.

See here for the macro definition:

diesel/diesel/src/type_impls/tuples.rs

Line 550 in 3f030a2

macro_rules! impl_sql_type {

As you can see this macro is relatively small in terms of code, it just generates a lot of impls. One "special" feature of this macro is to generate a lot of repetitive bounds. Now you could argue that we shouldn't to not generate that much code there. Well, we did that in the past and it caused compile times to explode. See #2480 for the details. I think the underlying rustc issue is still not fixed.

What I want to say with this example: We are aware that generated code has an impact on the compile times, but it is really not as simple as "just minimize the amount of code" to get better compile times. And given that we already optimize diesel for quite a while now I think most long hanging fruits are already gone.

Nevertheless if someone is interested in further optimizations I suggest that you take your application (not diesel itself) and have a look at the output of cargo llvm-lines. I think there are still a few places left where we could reduce the amount of generic code generated in downstream crates to speedup their compilation times. That seems to be a better optimization target than speeding up the compilation of diesel itself. While that is nice for me, it ultimately won't help you that much as I expect that you are mostly interested in the compilation time of your application

[Nutomic]

Thanks for the reply. Clearly you know a lot about these compiler internals and optimizations, for me its quite complicated. I did run llvm-lines on two of our crates, heres the output:

lemmy_db_schema (contains lots of insert forms and simple queries)

Lines                 Copies               Function name
-----                 ------               -------------
283718                22807                (TOTAL)
46981 (16.6%, 16.6%)  2361 (10.4%, 10.4%) core::option::Option::map
22395 (7.9%, 24.5%)    840 (3.7%, 14.0%)  diesel::expression_methods::global_expression_methods::ExpressionMethods::eq
15252 (5.4%, 29.8%)    762 (3.3%, 17.4%)   as diesel::query_builder::update_statement::changeset::AsChangeset>::as_changeset
14524 (5.1%, 34.9%)    718 (3.1%, 20.5%)   as diesel::insertable::Insertable<::Table>>::values
14440 (5.1%, 40.0%)    718 (3.1%, 23.7%)  core::option::Option::unwrap_or_default
4981 (1.8%, 41.8%)    718 (3.1%, 26.8%)  > as diesel::insertable::Insertable>::values
3021 (1.1%, 42.9%)    562 (2.5%, 29.3%)  core::ops::function::FnOnce::call_once
2720 (1.0%, 43.8%)    112 (0.5%, 29.8%)   as core::ops::drop::Drop>::drop
2207 (0.8%, 44.6%)     26 (0.1%, 29.9%)  diesel::type_impls::tuples::::as_changeset
2156 (0.8%, 45.4%)   1558 (6.8%, 36.7%)  diesel::query_builder::insert_statement::ValuesClause::new
2147 (0.8%, 46.1%)    718 (3.1%, 39.9%)  > as diesel::insertable::Insertable>::values::{{closure}}
2147 (0.8%, 46.9%)      4 (0.0%, 39.9%)  diesel::type_impls::tuples::::as_changeset
2096 (0.7%, 47.6%)    718 (3.1%, 43.0%)   as diesel::insertable::Insertable>::values
2057 (0.7%, 48.3%)     22 (0.1%, 43.1%)  diesel::type_impls::tuples:: for (T,T1,T2,T3)>::values
1964 (0.7%, 49.0%)     28 (0.1%, 43.3%)  diesel::type_impls::tuples:: for (T,T1,T2)>::values
1891 (0.7%, 49.7%)      6 (0.0%, 43.3%)  diesel::type_impls::tuples:: for (T,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12)>::values
1872 (0.7%, 50.3%)    762 (3.3%, 46.6%)  > as diesel::query_builder::update_statement::changeset::AsChangeset>::as_changeset
1860 (0.7%, 51.0%)     30 (0.1%, 46.8%)  diesel::type_impls::tuples::::as_changeset
1848 (0.7%, 51.7%)     24 (0.1%, 46.9%)  crossbeam_epoch::deferred::Deferred::new
1712 (0.6%, 52.3%)      6 (0.0%, 46.9%)  diesel::type_impls::tuples::::as_changeset
1708 (0.6%, 52.9%)    718 (3.1%, 50.0%)  > as diesel::insertable::Insertable>::values
1609 (0.6%, 53.4%)      6 (0.0%, 50.1%)  diesel::type_impls::tuples::::as_changeset
1606 (0.6%, 54.0%)      2 (0.0%, 50.1%)  diesel::type_impls::tuples:: for (T,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,T17,T18,T19,T20,T21,T22,T23,T24,T25,T26,T27,T28,T29,T30,T31,T32,T33)>::values
1452 (0.5%, 54.5%)      2 (0.0%, 50.1%)  diesel::type_impls::tuples::::as_changeset
1413 (0.5%, 55.0%)      2 (0.0%, 50.1%)  diesel::type_impls::tuples:: for (T,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,T17,T18,T19,T20,T21,T22,T23,T24,T25,T26,T27,T28,T29)>::values
1291 (0.5%, 55.5%)      2 (0.0%, 50.1%)  diesel::type_impls::tuples::::as_changeset
1282 (0.5%, 55.9%)      2 (0.0%, 50.1%)  diesel::type_impls::tuples:: for (T,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,T17,T18,T19,T20,T21,T22,T23,T24,T25)>::values
1268 (0.4%, 56.4%)     66 (0.3%, 50.4%)  alloc::boxed::Box::new
1240 (0.4%, 56.8%)    538 (2.4%, 52.8%)   as diesel::query_builder::update_statement::changeset::AsChangeset>::as_changeset
1230 (0.4%, 57.2%)      2 (0.0%, 52.8%)  diesel::type_impls::tuples:: for (T,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,T17,T18,T19,T20,T21,T22,T23)>::values
1180 (0.4%, 57.6%)     24 (0.1%, 52.9%)  diesel::type_impls::tuples:: for (T,T1)>::values
1175 (0.4%, 58.1%)      4 (0.0%, 52.9%)  diesel::type_impls::tuples:: for (T,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11)>::values
1146 (0.4%, 58.5%)      2 (0.0%, 52.9%)  diesel::type_impls::tuples::::as_changeset
1104 (0.4%, 58.9%)      8 (0.0%, 52.9%)  moka::cht::segment::HashMap::with_num_segments_capacity_and_hasher
1071 (0.4%, 59.2%)      3 (0.0%, 52.9%)  diesel_async::pg::AsyncPgConnection::with_prepared_statement_after_sql_built::{{closure}}::{{closure}}
1056 (0.4%, 59.6%)     48 (0.2%, 53.2%)  crossbeam_epoch::deferred::Deferred::new::call
1044 (0.4%, 60.0%)     18 (0.1%, 53.2%)  crossbeam_channel::counter::Receiver::release
1044 (0.4%, 60.3%)     18 (0.1%, 53.3%)  crossbeam_channel::counter::Sender::release
1032 (0.4%, 60.7%)     24 (0.1%, 53.4%)  crossbeam_epoch::guard::Guard::defer_unchecked
1025 (0.4%, 61.1%)    840 (3.7%, 57.1%)  diesel::expression::operators::Eq::new
1010 (0.4%, 61.4%)     22 (0.1%, 57.2%)   as core::ops::drop::Drop>::drop
1008 (0.4%, 61.8%)      2 (0.0%, 57.2%)  diesel::type_impls::tuples::::as_changeset
940 (0.3%, 62.1%)     22 (0.1%, 57.3%)  diesel::type_impls::tuples::::as_changeset

lemmy_db_views_report_combined (contains a complex query with lots of joins)

Lines               Copies             Function name
-----               ------             -------------
3345                137                (TOTAL)
1188 (35.5%, 35.5%)   1 (0.7%,  0.7%)  lemmy_db_views_report_combined::impls::::map_to_enum
299 (8.9%, 44.5%)    1 (0.7%,  1.5%)  ::clone
292 (8.7%, 53.2%)    1 (0.7%,  2.2%)  ::clone
215 (6.4%, 59.6%)    8 (5.8%,  8.0%)  diesel::expression_methods::bool_expression_methods::BoolExpressionMethods::or
204 (6.1%, 65.7%)    1 (0.7%,  8.8%)  ::clone
144 (4.3%, 70.0%)    1 (0.7%,  9.5%)  core::ptr::drop_in_place
111 (3.3%, 73.3%)    1 (0.7%, 10.2%)  core::ptr::drop_in_place
111 (3.3%, 76.7%)    1 (0.7%, 10.9%)  core::ptr::drop_in_place
78 (2.3%, 79.0%)    3 (2.2%, 13.1%)  diesel::expression_methods::bool_expression_methods::BoolExpressionMethods::and
78 (2.3%, 81.3%)    1 (0.7%, 13.9%)  core::ptr::drop_in_place
52 (1.6%, 82.9%)    2 (1.5%, 15.3%)  diesel::pg::expression::expression_methods::PgExpressionMethods::is_distinct_from
47 (1.4%, 84.3%)    1 (0.7%, 16.1%)  lemmy_db_views_report_combined::impls::::to_cursor
45 (1.3%, 85.6%)    1 (0.7%, 16.8%)  core::ptr::drop_in_place
39 (1.2%, 86.8%)    3 (2.2%, 19.0%)   as core::clone::Clone>::clone
34 (1.0%, 87.8%)    1 (0.7%, 19.7%)  core::ptr::drop_in_place
29 (0.9%, 88.7%)    1 (0.7%, 20.4%)  diesel::expression_methods::global_expression_methods::ExpressionMethods::lt
23 (0.7%, 89.4%)    1 (0.7%, 21.2%)  core::ptr::drop_in_place
23 (0.7%, 90.0%)    1 (0.7%, 21.9%)  core::ptr::drop_in_place
23 (0.7%, 90.7%)    1 (0.7%, 22.6%)  core::ptr::drop_in_place
12 (0.4%, 91.1%)   11 (8.0%, 30.7%)  >::as_expression
10 (0.3%, 91.4%)    8 (5.8%, 36.5%)  diesel::expression::operators::Or::new
10 (0.3%, 91.7%)    1 (0.7%, 37.2%)  lemmy_db_views_report_combined::impls::::get_report_count
10 (0.3%, 92.0%)    1 (0.7%, 38.0%)  lemmy_db_views_report_combined::impls::filter_admin_reports
9 (0.3%, 92.3%)    1 (0.7%, 38.7%)  lemmy_db_views_report_combined::impls::filter_mod_reports
8 (0.2%, 92.5%)    1 (0.7%, 39.4%)  core::ptr::drop_in_place>
8 (0.2%, 92.7%)    1 (0.7%, 40.1%)  core::ptr::drop_in_place>
8 (0.2%, 93.0%)    1 (0.7%, 40.9%)  core::ptr::drop_in_place>
8 (0.2%, 93.2%)    1 (0.7%, 41.6%)  core::ptr::drop_in_place>
8 (0.2%, 93.5%)    1 (0.7%, 42.3%)  core::ptr::drop_in_place>
8 (0.2%, 93.7%)    1 (0.7%, 43.1%)  core::ptr::drop_in_place>
8 (0.2%, 93.9%)    1 (0.7%, 43.8%)  core::ptr::drop_in_place>
8 (0.2%, 94.2%)    1 (0.7%, 44.5%)  core::ptr::drop_in_place>
8 (0.2%, 94.4%)    1 (0.7%, 45.3%)  core::ptr::drop_in_place>
8 (0.2%, 94.6%)    1 (0.7%, 46.0%)  core::ptr::drop_in_place>

To me nothing really stands out here, though maybe you notice something. Maybe the slow compilation is actually caused by generics. Do you know of any similar tools to analyze those? Or diesel-async and async in general could be responsible.

[weiznich]

There is nothing unexpected from diesels side in there. I honestly do not have the capacity to debug your project for you, so you are on your own with figuring out why it takes that long to compile.

Amos did write a good article on how to profile your compile times some time back. It's a good starting point for seeking what takes time. Especially the rustc self profile infrastructure has been helpful for me in the past. As written above: You need to do the actual profiling on your own, I just don't have any time to help other projects, I'm already over capacity with what needs to be done here.

[Nutomic]

Thanks, I didnt know that article yet.

[weiznich]

@Nutomic If you are interested with helping speeding up the compilation times for code depending on diesel. The code generated by the table! macro could be a good optimization target. I did some changes for the upcoming view support, including removing a single generic impl. For other reasons I did some compile time mesaruments and it seems like that has a significant impact on compile times already: #4901 (reply in thread)

That makes me believing that removing more of the generated impls there in favor of generic impls in diesel might help. Any impl related to alias or references might be a good candidate for that. You can find the expanded code here: https://docs.diesel.rs/main/diesel/macro.table.html#expanded-code-1

The relevant previous change to the table! macro is https://github.com/diesel-rs/diesel/pull/4811/changes#diff-7e4151696db3bea97c54ef05c9e967ffe78c7a79322b81ad74537ea2bc4160b5R15-R32 + the corresponding removal of the code from the code generated by table!