implement binary format of date and time types

README

@@ -31,7 +31,9 @@ Erlang PostgreSQL Database Client
   the unnamed prepared statement and portal. PostgreSQL's binary format
   is used to return integers as Erlang integers, floats as floats,
   bytea/text/varchar columns as binaries, bools as true/false, etc.
-  For details see pgsql_binary.erl.
+
+  For details see pgsql_binary.erl and the Data Representation section
+  below.
 
 * Parse/Bind/Execute
 
@@ -56,3 +58,22 @@ Erlang PostgreSQL Database Client
   ok = pgsql:close(C, Statement).
   ok = pgsql:close(C, statement | portal, Name).
   ok = pgsql:sync(C).
+
+* Data Representation
+
+  null        = null
+  bool        = true | false
+  char        = $A
+  intX        = 1
+  floatX      = 1.0
+  date        = {Year, Month, Day}
+  time        = {Hour, Minute, Second.Microsecond}
+  timetz      = {time, Timezone}
+  timestamp   = {date, time}
+  timestamptz = {date, time}
+  interval    = {time, Days, Months}
+  text        = <<"a">>
+  varchar     = <<"a">>
+  bytea       = <<1, 2>>
+
+  record      = {int2, time, text, ...} (decode only)

src/pgsql_binary.erl

@@ -15,6 +15,9 @@ encode(int4, N)     -> <<4:?int32, N:1/big-signed-unit:32>>;
 encode(int8, N)     -> <<8:?int32, N:1/big-signed-unit:64>>;
 encode(float4, N)   -> <<4:?int32, N:1/big-float-unit:32>>;
 encode(float8, N)   -> <<8:?int32, N:1/big-float-unit:64>>;
+encode(Type, B) when Type == time; Type == timetz          -> pgsql_datetime:encode(Type, B);
+encode(Type, B) when Type == date; Type == timestamp       -> pgsql_datetime:encode(Type, B);
+encode(Type, B) when Type == timestamptz; Type == interval -> pgsql_datetime:encode(Type, B);
 encode(bytea, B) when is_binary(B)   -> <<(byte_size(B)):?int32, B/binary>>;
 encode(text, B) when is_binary(B)    -> <<(byte_size(B)):?int32, B/binary>>;
 encode(varchar, B) when is_binary(B) -> <<(byte_size(B)):?int32, B/binary>>;
@@ -30,7 +33,10 @@ decode(int8, <<N:1/big-signed-unit:64>>)    -> N;
 decode(float4, <<N:1/big-float-unit:32>>)   -> N;
 decode(float8, <<N:1/big-float-unit:64>>)   -> N;
 decode(record, <<_:?int32, Rest/binary>>)   -> list_to_tuple(decode_record(Rest, []));
-decode(_Other, Bin)                         -> Bin.
+decode(Type, B) when Type == time; Type == timetz          -> pgsql_datetime:decode(Type, B);
+decode(Type, B) when Type == date; Type == timestamp       -> pgsql_datetime:decode(Type, B);
+decode(Type, B) when Type == timestamptz; Type == interval -> pgsql_datetime:decode(Type, B);
+decode(_Other, Bin) -> Bin.
 
 decode_record(<<>>, Acc) ->
     lists:reverse(Acc);
@@ -51,4 +57,10 @@ supports(bytea)   -> true;
 supports(text)    -> true;
 supports(varchar) -> true;
 supports(record)  -> true;
-supports(_Type)   -> false.
+supports(date)    -> true;
+supports(time)    -> true;
+supports(timetz)  -> true;
+supports(timestamp)   -> true;
+supports(timestamptz) -> true;
+supports(interval)    -> true;
+supports(_Type)       -> false.

src/pgsql_datetime.erl

@@ -0,0 +1,126 @@
+%%% Copyright (C) 2008 - Will Glozer.  All rights reserved.
+
+-module(pgsql_datetime).
+
+-export([decode/2, encode/2]).
+
+-define(int16, 1/big-signed-unit:16).
+-define(int32, 1/big-signed-unit:32).
+
+-define(postgres_epoc_jdate, 2451545).
+
+-define(mins_per_hour, 60).
+-define(secs_per_day, 86400.0).
+-define(secs_per_hour, 3600.0).
+-define(secs_per_minute, 60.0).
+
+decode(date, <<J:1/big-signed-unit:32>>)             -> j2date(?postgres_epoc_jdate + J);
+decode(time, <<N:1/big-float-unit:64>>)              -> f2time(N);
+decode(timetz, <<N:1/big-float-unit:64, TZ:?int32>>) -> {f2time(N), TZ};
+decode(timestamp, <<N:1/big-float-unit:64>>)         -> f2timestamp(N);
+decode(timestamptz, <<N:1/big-float-unit:64>>)       -> f2timestamp(N);
+decode(interval, <<N:1/big-float-unit:64, D:?int32, M:?int32>>) -> {f2time(N), D, M}.
+
+encode(date, D)         -> <<4:?int32, (date2j(D) - ?postgres_epoc_jdate):1/big-signed-unit:32>>;
+encode(time, T)         -> <<8:?int32, (time2f(T)):1/big-float-unit:64>>;
+encode(timetz, {T, TZ}) -> <<12:?int32, (time2f(T)):1/big-float-unit:64, TZ:?int32>>;
+encode(timestamp, TS)   -> <<8:?int32, (timestamp2f(TS)):1/big-float-unit:64>>;
+encode(timestamptz, TS) -> <<8:?int32, (timestamp2f(TS)):1/big-float-unit:64>>;
+encode(interval, {T, D, M}) -> <<16:?int32, (time2f(T)):1/big-float-unit:64, D:?int32, M:?int32>>.
+
+j2date(N) ->
+    J = N + 32044,
+    Q1 = J div 146097,
+    Extra = (J - Q1 * 146097) * 4 + 3,
+    J2 = J + 60 + Q1 * 3 + Extra div 146097,
+    Q2 = J2 div 1461,
+    J3 = J2 - Q2 * 1461,
+    Y = J3 * 4 div 1461,
+    case Y of
+        0 -> J4 = ((J3 + 306) rem 366) + 123;
+        _ -> J4 = ((J3 + 305) rem 365) + 123
+    end,
+    Year = (Y + Q2 * 4) - 4800,
+    Q3 = J4 * 2141 div 65536,
+    Day = J4 - 7834 * Q3 div 256,
+    Month = (Q3 + 10) rem 12 + 1,
+    {Year, Month, Day}.
+
+date2j({Y, M, D}) ->
+    case M > 2 of
+        true ->
+            M2 = M + 1,
+            Y2 = Y + 4800;
+        false ->
+            M2 = M + 13,
+            Y2 = Y + 4799
+    end,
+    C = Y2 div 100,
+    J1 = Y2 * 365 - 32167,
+    J2 = J1 + (Y2 div 4 - C + C div 4),
+    J2 + 7834 * M2 div 256 + D.
+
+f2time(N) ->
+    {R1, Hour} = tmodulo(N, ?secs_per_hour),
+    {R2, Min}  = tmodulo(R1, ?secs_per_minute),
+    {R3, Sec}  = tmodulo(R2, 1.0),
+    case timeround(R3) of
+        US when US >= 1.0 -> f2time(ceiling(N));
+        US                -> {Hour, Min, Sec + US}
+    end.
+
+time2f({H, M, S}) ->
+    ((H * ?mins_per_hour + M) * ?secs_per_minute) + S.
+
+f2timestamp(N) ->
+    case tmodulo(N, ?secs_per_day) of
+        {T, D} when T < 0 -> f2timestamp2(D - 1 + ?postgres_epoc_jdate, T + ?secs_per_day);
+        {T, D}            -> f2timestamp2(D + ?postgres_epoc_jdate, T)
+    end.
+
+f2timestamp2(D, T) ->
+    {_H, _M, S} = Time = f2time(T),
+    Date = j2date(D),
+    case tsround(S - trunc(S)) of
+        N when N >= 1.0 ->
+            case ceiling(T) of
+                T2 when T2 > ?secs_per_day -> f2timestamp2(D + 1, 0.0);
+                T2                         -> f2timestamp2(T2, D)
+            end;
+        _ -> ok
+    end,
+    {Date, Time}.
+
+timestamp2f({Date, Time}) ->
+    D = date2j(Date) - ?postgres_epoc_jdate,
+    D * ?secs_per_day + time2f(Time).
+
+tmodulo(T, U) ->
+    case T < 0 of
+        true  -> Q = ceiling(T / U);
+        false -> Q = floor(T / U)
+    end,
+    case Q of
+        0 -> {T, Q};
+        _ -> {T - rint(Q * U), Q}
+    end.
+
+rint(N)      -> round(N) * 1.0.
+timeround(J) -> rint(J * 10000000000.0) / 10000000000.0.
+tsround(J)   -> rint(J * 1000000.0) / 1000000.0.
+
+floor(X) ->
+    T = erlang:trunc(X),
+    case (X - T) of
+        N when N < 0 -> T - 1;
+        N when N > 0 -> T;
+        _            -> T
+    end.
+
+ceiling(X) ->
+    T = erlang:trunc(X),
+    case (X - T) of
+        N when N < 0 -> T;
+        N when N > 0 -> T + 1;
+        _            -> T
+    end.

test_src/pgsql_tests.erl

@@ -331,53 +331,24 @@ parameter_set_test() ->
               {ok, _Cols, [{<<"02.01.2000">>}]} = pgsql:squery(C, "select '2000-01-02'::date")
       end).
 
-decode_binary_format_test() ->
-    with_connection(
-      fun(C) ->
-              {ok, [#column{type = unknown}], [{null}]} = pgsql:equery(C, "select null"),
-              {ok, [#column{type = bool}], [{true}]} = pgsql:equery(C, "select true"),
-              {ok, [#column{type = bool}], [{false}]} = pgsql:equery(C, "select false"),
-              {ok, [#column{type = bpchar}], [{$A}]} = pgsql:equery(C, "select 'A'::char"),
-              {ok, [#column{type = int2}], [{1}]} = pgsql:equery(C, "select 1::int2"),
-              {ok, [#column{type = int2}], [{-1}]} = pgsql:equery(C, "select -1::int2"),
-              {ok, [#column{type = int4}], [{1}]} = pgsql:equery(C, "select 1::int4"),
-              {ok, [#column{type = int4}], [{-1}]} = pgsql:equery(C, "select -1::int4"),
-              {ok, [#column{type = int8}], [{1}]} = pgsql:equery(C, "select 1::int8"),
-              {ok, [#column{type = int8}], [{-1}]} = pgsql:equery(C, "select -1::int8"),
-              {ok, [#column{type = float4}], [{1.0}]} = pgsql:equery(C, "select 1.0::float4"),
-              {ok, [#column{type = float4}], [{-1.0}]} = pgsql:equery(C, "select -1.0::float4"),
-              {ok, [#column{type = float8}], [{1.0}]} = pgsql:equery(C, "select 1.0::float8"),
-              {ok, [#column{type = float8}], [{-1.0}]} = pgsql:equery(C, "select -1.0::float8"),
-              {ok, [#column{type = bytea}], [{<<1, 2>>}]} = pgsql:equery(C, "select E'\001\002'::bytea"),
-              {ok, [#column{type = text}], [{<<"hi">>}]} = pgsql:equery(C, "select 'hi'::text"),
-              {ok, [#column{type = varchar}], [{<<"hi">>}]} = pgsql:equery(C, "select 'hi'::varchar"),
-              {ok, [#column{type = record}], [{{1, null, <<"hi">>}}]} = pgsql:equery(C, "select (1, null, 'hi')")
-      end).
-
-encode_binary_format_test() ->
-    with_connection(
-      fun(C) ->
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_bool) values ($1)", [null]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_bool) values ($1)", [true]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_bool) values ($1)", [false]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_char) values ($1)", [$A]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_int2) values ($1)", [1]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_int2) values ($1)", [-1]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_int4) values ($1)", [1]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_int4) values ($1)", [-1]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_int8) values ($1)", [1]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_int8) values ($1)", [-1]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_float4) values ($1)", [1.0]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_float4) values ($1)", [-1.0]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_float8) values ($1)", [1.0]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_float8) values ($1)", [-1.0]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_bytea) values ($1)", [<<1, 2>>]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_bytea) values ($1)", [[1, 2]]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_text) values ($1)", [<<"hi">>]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_text) values ($1)", ["hi"]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_varchar) values ($1)", [<<"hi">>]),
-              {ok, 1} = pgsql:equery(C, "insert into test_table2 (c_varchar) values ($1)", ["hi"])
-      end).
+type_test() ->
+    check_type(bool, "true", true, [true, false]),
+    check_type(bpchar, "'A'", $A, [1, $1, 255], "c_char"),
+    check_type(int2, "1", 1, [0, 256, -32768, +32767]),
+    check_type(int4, "1", 1, [0, 512, -2147483648, +2147483647]),
+    check_type(int8, "1", 1, [0, 1024, -9223372036854775808, +9223372036854775807]),
+    check_type(float4, "1.0", 1.0, [0.0, 1.23456, -1.23456]),
+    check_type(float8, "1.0", 1.0, [0.0, 1.23456789012345, -1.23456789012345]),
+    check_type(bytea, "E'\001\002'", <<1,2>>, [<<>>, <<0,128,255>>]),
+    check_type(text, "'hi'", <<"hi">>, [<<"">>, <<"hi">>]),
+    check_type(varchar, "'hi'", <<"hi">>, [<<"">>, <<"hi">>]),
+    check_type(date, "'2008-01-02'", {2008,1,2}, [{-4712,1,1}, {5874897,1,1}]),
+    check_type(time, "'00:01:02'", {0,1,2.0}, [{0,0,0.0}, {24,0,0.0}]),
+    check_type(timetz, "'00:01:02-01'", {{0,1,2.0},1*60*60}, [{{0,0,0.0},0}, {{24,0,0.0},-13*60*60}]),
+    check_type(timestamp, "'2008-01-02 03:04:05'", {{2008,1,2},{3,4,5.0}},
+               [{{-4712,1,1},{0,0,0.0}}, {{5874897,12,31}, {23,59,59.0}}]),
+    check_type(interval, "'1 hour 2 minutes 3.1 seconds'", {{1,2,3.1},0,0},
+               [{{0,0,0.0},0,-178000000 * 12}, {{0,0,0.0},0,178000000 * 12}]).
 
 text_format_test() ->
     with_connection(
@@ -388,9 +359,7 @@ text_format_test() ->
                                {ok, _Cols, [{V2}]} = pgsql:equery(C, Query, [V]),
                                {ok, _Cols, [{V2}]} = pgsql:equery(C, Query, [V2])
                        end,
-              Select("timestamp", "2000-01-02 03:04:05"),
-              Select("date", "2000-01-02"),
-              Select("time", "03:04:05"),
+              Select("inet", "127.0.0.1"),
               Select("numeric", "123456")
       end).
 
@@ -429,6 +398,34 @@ with_rollback(F) ->
                   end
       end).
 
+check_type(Type, In, Out, Values) ->
+    Column = "c_" ++ atom_to_list(Type),
+    check_type(Type, In, Out, Values, Column).
+
+check_type(Type, In, Out, Values, Column) ->
+    with_connection(
+      fun(C) ->
+              Select = io_lib:format("select ~s::~w", [In, Type]),
+              {ok, [#column{type = Type}], [{Out}]} = pgsql:equery(C, Select),
+              Sql = io_lib:format("insert into test_table2 (~s) values ($1) returning ~s", [Column, Column]),
+              {ok, #statement{columns = [#column{type = Type}]} = S} = pgsql:parse(C, Sql),
+              Insert = fun(V) ->
+                               pgsql:bind(C, S, [V]),
+                               {ok, 1, [{V2}]} = pgsql:execute(C, S),
+                               case compare(Type, V, V2) of
+                                   true  -> ok;
+                                   false -> ?debugFmt("~p =/= ~p~n", [V, V2]), ?assert(false)
+                               end,
+                               ok = pgsql:sync(C)
+                       end,
+              lists:foreach(Insert, [null | Values])
+      end).
+
+compare(_Type, null, null) -> true;
+compare(float4, V1, V2)    -> abs(V2 - V1) < 0.000001;
+compare(float8, V1, V2)    -> abs(V2 - V1) < 0.000000000000001;
+compare(_Type, V1, V2)     -> V1 =:= V2.
+
 %% flush mailbox
 flush() ->
     ?assertEqual([], flush([])).

test_src/test_schema.sql

@@ -39,7 +39,13 @@ CREATE TABLE test_table2 (
   c_float8 float8,
   c_bytea bytea,
   c_text text,
-  c_varchar varchar(64));
+  c_varchar varchar(64),
+  c_date date,
+  c_time time,
+  c_timetz timetz,
+  c_timestamp timestamp,
+  c_timestamptz timestamptz,
+  c_interval interval);
 
 CREATE LANGUAGE plpgsql;