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doc: Add section for temporal tables
This section introduces temporal tables, with a focus on Application Time (which we support) and only a brief mention of System Time (which we don't). It covers temporal primary keys, unique constraints, and temporal foreign keys. We will document temporal update/delete and periods as we add those features. This commit also adds glossary entries for temporal table, application time, and system time. Author: Paul A. Jungwirth <pj@illuminatedcomputing.com> Discussion: https://www.postgresql.org/message-id/flat/ec498c3d-5f2b-48ec-b989-5561c8aa2024@illuminatedcomputing.com
This commit is contained in:
Peter Eisentraut
@@ -1585,6 +1585,298 @@ CREATE TABLE circles (
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</para>
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</para>
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</sect1>
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</sect1>
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<sect1 id="ddl-temporal-tables">
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<title>Temporal Tables</title>
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<indexterm zone="ddl-temporal-tables">
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<primary>temporal</primary>
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</indexterm>
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<para>
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<firstterm>Temporal tables</firstterm> allow users to track different
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dimensions of history. <firstterm>Application time</firstterm> tracks the
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history of a thing out in the world, and <firstterm>system time</firstterm>
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tracks the history of the database itself. (A database that does both is
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also called <firstterm>bitemporal</firstterm>.) This section describes how
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to express and manage such histories in temporal tables.
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</para>
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<sect2 id="ddl-application-time">
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<title>Application Time</title>
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<indexterm zone="ddl-application-time">
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<primary>application time</primary>
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</indexterm>
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<para>
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<firstterm>Application time</firstterm> refers to a history of the entity
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described by a table. In a typical non-temporal table, there is single
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row for each entity. In a temporal table, an entity may have multiple
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rows, as long as those rows describe non-overlapping periods from its
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history. Application time requires each row to have a start and end time,
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expressing when the row is applicable.
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</para>
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<para>
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The following SQL creates a temporal table that can store application time:
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<programlisting>
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CREATE TABLE products (
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product_no integer,
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price numeric,
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<emphasis>valid_at daterange</emphasis>
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);
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</programlisting>
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</para>
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<para>
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Records in a temporal table can be imagined on a timeline, as in <xref
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linkend="temporal-entities-figure"/>. Here we show three records
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describing two products. Each record is a tuple with three attributes:
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the product number, the price, and the application time. So product 5 was
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first offered for a price of 5.00 starting January 1, 2020, but then
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became 8.00 starting January 1, 2022. Its second record has no specified
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end time, indicating that it is true indefinitely, or for all future time.
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The last record shows that product 6 was introduced January 1, 2021 for
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9.00, then canceled January 1, 2024.
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</para>
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<figure id="temporal-entities-figure">
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<title>Application Time Example</title>
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<mediaobject>
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<imageobject>
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<imagedata fileref="images/temporal-entities.svg" format="SVG" width="100%"/>
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</imageobject>
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</mediaobject>
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</figure>
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<para>
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In a table, these records would be:
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<programlisting>
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product_no | price | valid_at
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------------+-------+-------------------------
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5 | 5.00 | [2020-01-01,2022-01-01)
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5 | 8.00 | [2022-01-01,)
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6 | 9.00 | [2021-01-01,2024-01-01)
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</programlisting>
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</para>
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<para>
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We show the application time using range-type notation, because it is
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stored as a single column (either a range or multirange). Ranges include
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their start point but exclude their end point. That way two adjacent
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ranges cover all points without overlapping. See <xref
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linkend="rangetypes"/> for more information about range types.
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</para>
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<para>
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In principle, a table with application-time ranges/multiranges is
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equivalent to a table that stores application-time
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<quote>instants</quote>: one for each second, millisecond, nanosecond, or
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whatever finest granularity is available. But such a table would contain
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far too many rows, so ranges/multiranges offer an optimization to
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represent the same information in a compact form. In addition, ranges and
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multiranges offer a more convenient interface for typical temporal
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operations, where records change infrequently enough that separate
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<quote>versions</quote> persist for extended periods of time.
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</para>
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<sect3 id="ddl-application-time-primary-keys">
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<title>Temporal Primary Keys and Unique Constraints</title>
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<para>
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A table with application time has a different concept of entity
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uniqueness than a non-temporal table. Temporal entity uniqueness can be
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enforced with a temporal primary key. A regular primary key has at least
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one column, all columns are <literal>NOT NULL</literal>, and the combined
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value of all columns is unique. A temporal primary key also has at least
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one such column, but in addition it has a final column that is of a range
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type or multirange type that shows when the row is applicable. The
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regular parts of the key must be unique for any moment in time, but
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non-unique rows are allowed if their application time does not overlap.
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</para>
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<para>
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The syntax to create a temporal primary key is as follows:
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<programlisting>
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CREATE TABLE products (
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product_no integer,
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price numeric,
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valid_at daterange,
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<emphasis>PRIMARY KEY (product_no, valid_at WITHOUT OVERLAPS)</emphasis>
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);
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</programlisting>
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In this example, <literal>product_no</literal> is the non-temporal part
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of the key, and <literal>valid_at</literal> is a range column containing
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the application time.
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</para>
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<para>
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The <literal>WITHOUT OVERLAPS</literal> column is implicitly <literal>NOT
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NULL</literal> (like the other parts of the key). In addition it may not
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contain empty values, that is, a range of <literal>'empty'</literal> or a
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multirange of <literal>{}</literal>. An empty application time would
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have no meaning.
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</para>
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<para>
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It is also possible to create a temporal unique constraint that is
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not a primary key. The syntax is similar:
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<programlisting>
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CREATE TABLE products (
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product_no integer,
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price numeric,
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valid_at daterange,
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<emphasis>UNIQUE (product_no, valid_at WITHOUT OVERLAPS)</emphasis>
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);
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</programlisting>
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Temporal unique constraints also forbid empty ranges/multiranges for
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their application time, but that column is permitted to be null (like the
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other columns of the unique constraint).
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</para>
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<para>
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Temporal primary keys and unique constraints are backed by GiST indexes
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(see <xref linkend="gist"/>) rather than B-Tree indexes. In practice,
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creating a temporal primary key or constraint requires installing the
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<xref linkend="btree-gist"/> extension, so that the database has GiST
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operator classes for the non-temporal parts of the key.
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</para>
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<para>
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Temporal primary keys and unique constraints have the same behavior as
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exclusion constraints (see <xref linkend="ddl-constraints-exclusion"/>),
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where each regular key part is compared with equality, and the
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application time is compared with overlaps, for example <literal>EXCLUDE
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USING gist (id WITH =, valid_at WITH &&)</literal>. The only
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difference is that they also forbid an empty application time.
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</para>
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</sect3>
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<sect3 id="ddl-application-time-foreign-keys">
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<title>Temporal Foreign Keys</title>
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<para>
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A temporal foreign key is a reference from one application-time table to
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another application-time table. Just as a non-temporal reference
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requires a referenced key to exist, so a temporal reference requires a
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referenced key to exist, but during whatever history the reference exists
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(at least). So if the <literal>products</literal> table is referenced by
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a <literal>variants</literal> table, and a variant of product 5 has an
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application-time of <literal>[2020-01-01,2026-01-01)</literal>, then
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product 5 must exist throughout that period.
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</para>
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<para>
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We can create the <literal>variants</literal> table with the following
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schema (without a foreign key yet):
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<programlisting>
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CREATE TABLE variants (
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id integer,
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product_no integer,
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name text,
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valid_at daterange,
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PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
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);
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</programlisting>
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We have included a temporal primary key as a best practice, but it is not
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strictly required by foreign keys.
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</para>
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<para>
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<xref linkend="temporal-references-figure"/> plots product 5 (in green)
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and two variants referencing it (in yellow) on the same timeline.
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Variant 8 (Medium) was introduced first, then variant 9 (XXL). Both
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satisfy the foreign key constraint, because the referenced product exists
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throughout their entire history.
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</para>
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<figure id="temporal-references-figure">
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<title>Temporal Foreign Key Example</title>
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<mediaobject>
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<imageobject>
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<imagedata fileref="images/temporal-references.svg" format="SVG" width="100%"/>
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</imageobject>
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</mediaobject>
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</figure>
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<para>
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In a table, these records would be:
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<programlisting>
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id | product_no | name | valid_at
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----+------------+--------+-------------------------
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8 | 5 | Medium | [2021-01-01,2023-06-01)
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9 | 5 | XXL | [2022-03-01,2024-06-01)
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</programlisting>
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</para>
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<para>
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Note that a temporal reference need not be fulfilled by a single row in
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the referenced table. Product 5 had a price change in the middle of
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variant 8's history, but the reference is still valid. The combination
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of all matching rows is used to test whether the referenced history
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contains the referencing row.
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</para>
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<para>
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The syntax to add a temporal foreign key to our table is:
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<programlisting>
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CREATE TABLE variants (
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id integer,
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product_no integer,
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name text,
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valid_at daterange,
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PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
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<emphasis>FOREIGN KEY (product_no, PERIOD valid_at) REFERENCES products (product_no, PERIOD valid_at)</emphasis>
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);
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</programlisting>
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Note that the keyword <literal>PERIOD</literal> must be used for the
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application-time column in both the referencing and referenced table.
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</para>
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<para>
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A temporal primary key or unique constraint matching the referenced columns
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must exist on the referenced table.
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</para>
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<para>
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<productname>PostgreSQL</productname> supports temporal foreign keys with
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action <literal>NO ACTION</literal>, but not <literal>RESTRICT</literal>,
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<literal>CASCADE</literal>, <literal>SET NULL</literal>, or <literal>SET
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DEFAULT</literal>.
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</para>
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</sect3>
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</sect2>
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<sect2 id="ddl-system-time">
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<title>System Time</title>
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<indexterm zone="ddl-system-time">
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<primary>system time</primary>
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</indexterm>
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<para>
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<firstterm>System time</firstterm> refers to the history of the database
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table, not the entity it describes. It captures when each row was
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inserted/updated/deleted.
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</para>
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<para>
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<productname>PostgreSQL</productname> does not currently support system
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time, but it could be emulated using triggers, and there are external
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extensions that provide such functionality.
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</para>
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</sect2>
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</sect1>
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<sect1 id="ddl-alter">
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<sect1 id="ddl-alter">
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<title>Modifying Tables</title>
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<title>Modifying Tables</title>
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@@ -81,6 +81,21 @@
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</glossdef>
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</glossdef>
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</glossentry>
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</glossentry>
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<glossentry id="glossary-application-time">
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<glossterm>Application time</glossterm>
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<glossdef>
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<para>
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In a <glossterm linkend="glossary-temporal-table">temporal table</glossterm>,
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|
the dimension of time that represents when the entity described by the table
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|
changed (as opposed to the table itself).
|
||||||
|
</para>
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|
<para>
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||||||
|
For more information, see
|
||||||
|
<xref linkend="ddl-temporal-tables"/>.
|
||||||
|
</para>
|
||||||
|
</glossdef>
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|
</glossentry>
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|
|
||||||
<glossentry id="glossary-aio">
|
<glossentry id="glossary-aio">
|
||||||
<glossterm>Asynchronous <acronym>I/O</acronym></glossterm>
|
<glossterm>Asynchronous <acronym>I/O</acronym></glossterm>
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<acronym>AIO</acronym>
|
<acronym>AIO</acronym>
|
||||||
@@ -1847,6 +1862,22 @@
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</glossdef>
|
</glossdef>
|
||||||
</glossentry>
|
</glossentry>
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||||||
|
|
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|
<glossentry id="glossary-system-time">
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<glossterm>System time</glossterm>
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||||||
|
<glossdef>
|
||||||
|
<para>
|
||||||
|
In a <glossterm linkend="glossary-temporal-table">temporal table</glossterm>,
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||||||
|
the dimension of time that represents when the table itself was changed
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||||||
|
(as opposed to the entity the table describes).
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|
Often used for auditing, compliance, and debugging.
|
||||||
|
</para>
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||||||
|
<para>
|
||||||
|
For more information, see
|
||||||
|
<xref linkend="ddl-temporal-tables"/>.
|
||||||
|
</para>
|
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|
</glossdef>
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||||||
|
</glossentry>
|
||||||
|
|
||||||
<glossentry id="glossary-table">
|
<glossentry id="glossary-table">
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||||||
<glossterm>Table</glossterm>
|
<glossterm>Table</glossterm>
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||||||
<glossdef>
|
<glossdef>
|
||||||
@@ -1885,6 +1916,22 @@
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|||||||
</glossdef>
|
</glossdef>
|
||||||
</glossentry>
|
</glossentry>
|
||||||
|
|
||||||
|
<glossentry id="glossary-temporal-table">
|
||||||
|
<glossterm>Temporal table</glossterm>
|
||||||
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<glossdef>
|
||||||
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<para>
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||||||
|
<glossterm linkend="glossary-table">Tables</glossterm>
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||||||
|
that track <glossterm linkend="glossary-application-time">application time</glossterm>
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or <glossterm linkend="glossary-system-time">system time</glossterm> (or both).
|
||||||
|
Not to be confused with <glossterm linkend="glossary-temporary-table">temporary tables</glossterm>.
|
||||||
|
</para>
|
||||||
|
<para>
|
||||||
|
For more information, see
|
||||||
|
<xref linkend="ddl-temporal-tables"/>.
|
||||||
|
</para>
|
||||||
|
</glossdef>
|
||||||
|
</glossentry>
|
||||||
|
|
||||||
<glossentry id="glossary-temporary-table">
|
<glossentry id="glossary-temporary-table">
|
||||||
<glossterm>Temporary table</glossterm>
|
<glossterm>Temporary table</glossterm>
|
||||||
<glossdef>
|
<glossdef>
|
||||||
|
|||||||
@@ -5,7 +5,9 @@
|
|||||||
ALL_IMAGES = \
|
ALL_IMAGES = \
|
||||||
genetic-algorithm.svg \
|
genetic-algorithm.svg \
|
||||||
gin.svg \
|
gin.svg \
|
||||||
pagelayout.svg
|
pagelayout.svg \
|
||||||
|
temporal-entities.svg \
|
||||||
|
temporal-references.svg
|
||||||
|
|
||||||
DITAA = ditaa
|
DITAA = ditaa
|
||||||
DOT = dot
|
DOT = dot
|
||||||
|
|||||||
34
doc/src/sgml/images/temporal-entities.svg
Normal file
34
doc/src/sgml/images/temporal-entities.svg
Normal file
@@ -0,0 +1,34 @@
|
|||||||
|
<?xml version="1.0"?>
|
||||||
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1020 252" width="1020" height="252" shape-rendering="geometricPrecision" version="1.0">
|
||||||
|
<defs>
|
||||||
|
<filter id="f2" x="0" y="0" width="200%" height="200%">
|
||||||
|
<feOffset result="offOut" in="SourceGraphic" dx="5" dy="5"/>
|
||||||
|
<feGaussianBlur result="blurOut" in="offOut" stdDeviation="3"/>
|
||||||
|
<feBlend in="SourceGraphic" in2="blurOut" mode="normal"/>
|
||||||
|
</filter>
|
||||||
|
</defs>
|
||||||
|
<g stroke-width="1" stroke-linecap="square" stroke-linejoin="round">
|
||||||
|
<rect x="0" y="0" width="1020" height="252" style="fill: #ffffff"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#99dd99" d="M215.0 105.0 L215.0 175.0 L785.0 175.0 L785.0 105.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#99dd99" d="M965.0 35.0 L965.0 105.0 L405.0 105.0 L405.0 35.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#99dd99" d="M25.0 35.0 L25.0 105.0 L405.0 105.0 L405.0 35.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M25.0 196.0 L25.0 209.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M405.0 196.0 L405.0 209.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M215.0 196.0 L215.0 209.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M595.0 196.0 L595.0 209.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M785.0 196.0 L785.0 209.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M975.0 196.0 L975.0 209.0 "/>
|
||||||
|
<text x="40" y="68" font-family="Courier" font-size="15" stroke="none" fill="#000000">products</text>
|
||||||
|
<text x="40" y="82" font-family="Courier" font-size="15" stroke="none" fill="#000000">(5, 5.00, [1 Jan 2020,1 Jan 2022))</text>
|
||||||
|
<text x="20" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">2020</text>
|
||||||
|
<text x="230" y="138" font-family="Courier" font-size="15" stroke="none" fill="#000000">products</text>
|
||||||
|
<text x="230" y="152" font-family="Courier" font-size="15" stroke="none" fill="#000000">(6, 9.00, [1 Jan 2021,1 Jan 2024))</text>
|
||||||
|
<text x="210" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">2021</text>
|
||||||
|
<text x="400" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">2022</text>
|
||||||
|
<text x="420" y="68" font-family="Courier" font-size="15" stroke="none" fill="#000000">products</text>
|
||||||
|
<text x="420" y="82" font-family="Courier" font-size="15" stroke="none" fill="#000000">(5, 8.00, [1 Jan 2022,))</text>
|
||||||
|
<text x="590" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">2023</text>
|
||||||
|
<text x="780" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">2024</text>
|
||||||
|
<text x="979" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">...</text>
|
||||||
|
</g>
|
||||||
|
</svg>
|
||||||
|
After Width: | Height: | Size: 3.2 KiB |
14
doc/src/sgml/images/temporal-entities.txt
Normal file
14
doc/src/sgml/images/temporal-entities.txt
Normal file
@@ -0,0 +1,14 @@
|
|||||||
|
+-------------------------------------+-------------------------------------------------------+
|
||||||
|
| cGRE | cGRE |
|
||||||
|
| products | products |
|
||||||
|
| (5, 5.00, [1 Jan 2020,1 Jan 2022)) | (5, 8.00, [1 Jan 2022,)) |
|
||||||
|
| | |
|
||||||
|
+------------------+------------------+-------------------------------------+-----------------+
|
||||||
|
| cGRE |
|
||||||
|
| products |
|
||||||
|
| (6, 9.00, [1 Jan 2021,1 Jan 2024)) |
|
||||||
|
| |
|
||||||
|
+--------------------------------------------------------+
|
||||||
|
|
||||||
|
| | | | | |
|
||||||
|
2020 2021 2022 2023 2024 ...
|
||||||
37
doc/src/sgml/images/temporal-references.svg
Normal file
37
doc/src/sgml/images/temporal-references.svg
Normal file
@@ -0,0 +1,37 @@
|
|||||||
|
<?xml version="1.0"?>
|
||||||
|
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1020 322" width="1020" height="322" shape-rendering="geometricPrecision" version="1.0">
|
||||||
|
<defs>
|
||||||
|
<filter id="f2" x="0" y="0" width="200%" height="200%">
|
||||||
|
<feOffset result="offOut" in="SourceGraphic" dx="5" dy="5"/>
|
||||||
|
<feGaussianBlur result="blurOut" in="offOut" stdDeviation="3"/>
|
||||||
|
<feBlend in="SourceGraphic" in2="blurOut" mode="normal"/>
|
||||||
|
</filter>
|
||||||
|
</defs>
|
||||||
|
<g stroke-width="1" stroke-linecap="square" stroke-linejoin="round">
|
||||||
|
<rect x="0" y="0" width="1020" height="322" style="fill: #ffffff"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#99dd99" d="M395.0 105.0 L395.0 35.0 L945.0 35.0 L945.0 105.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#ffff33" d="M215.0 105.0 L215.0 175.0 L685.0 175.0 L685.0 105.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#ffff33" d="M455.0 175.0 L875.0 175.0 L875.0 245.0 L455.0 245.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="#99dd99" d="M25.0 35.0 L25.0 105.0 L395.0 105.0 L395.0 35.0 z"/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M25.0 266.0 L25.0 279.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M405.0 266.0 L405.0 279.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M215.0 266.0 L215.0 279.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M595.0 266.0 L595.0 279.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M785.0 266.0 L785.0 279.0 "/>
|
||||||
|
<path stroke="#000000" stroke-width="1.000000" stroke-linecap="round" stroke-linejoin="round" fill="none" d="M975.0 266.0 L975.0 279.0 "/>
|
||||||
|
<text x="40" y="68" font-family="Courier" font-size="15" stroke="none" fill="#000000">products</text>
|
||||||
|
<text x="40" y="82" font-family="Courier" font-size="15" stroke="none" fill="#000000">(5, 5.00, [1 Jan 2020,1 Jan 2022))</text>
|
||||||
|
<text x="210" y="292" font-family="Courier" font-size="15" stroke="none" fill="#000000">2021</text>
|
||||||
|
<text x="230" y="138" font-family="Courier" font-size="15" stroke="none" fill="#000000">variants</text>
|
||||||
|
<text x="230" y="152" font-family="Courier" font-size="15" stroke="none" fill="#000000">(8, 5, 'Medium', [1 Jan 2021,1 Jun 2023))</text>
|
||||||
|
<text x="20" y="292" font-family="Courier" font-size="15" stroke="none" fill="#000000">2020</text>
|
||||||
|
<text x="470" y="208" font-family="Courier" font-size="15" stroke="none" fill="#000000">variants</text>
|
||||||
|
<text x="470" y="222" font-family="Courier" font-size="15" stroke="none" fill="#000000">(9, 5, 'XXL', [1 Mar 2022,1 Jun 2024))</text>
|
||||||
|
<text x="410" y="68" font-family="Courier" font-size="15" stroke="none" fill="#000000">products</text>
|
||||||
|
<text x="410" y="82" font-family="Courier" font-size="15" stroke="none" fill="#000000">(5, 8.00, [1 Jan 2022,))</text>
|
||||||
|
<text x="590" y="292" font-family="Courier" font-size="15" stroke="none" fill="#000000">2023</text>
|
||||||
|
<text x="400" y="292" font-family="Courier" font-size="15" stroke="none" fill="#000000">2022</text>
|
||||||
|
<text x="780" y="292" font-family="Courier" font-size="15" stroke="none" fill="#000000">2024</text>
|
||||||
|
<text x="979" y="292" font-family="Courier" font-size="15" stroke="none" fill="#000000">...</text>
|
||||||
|
</g>
|
||||||
|
</svg>
|
||||||
|
After Width: | Height: | Size: 3.7 KiB |
19
doc/src/sgml/images/temporal-references.txt
Normal file
19
doc/src/sgml/images/temporal-references.txt
Normal file
@@ -0,0 +1,19 @@
|
|||||||
|
+------------------------------------+------------------------------------------------------+
|
||||||
|
| cGRE | cGRE |
|
||||||
|
| products | products |
|
||||||
|
| (5, 5.00, [1 Jan 2020,1 Jan 2022)) | (5, 8.00, [1 Jan 2022,)) |
|
||||||
|
| | |
|
||||||
|
+------------------+-----------------+----------------------------+-------------------------+
|
||||||
|
| cYEL |
|
||||||
|
| variants |
|
||||||
|
| (8, 5, 'Medium', [1 Jan 2021,1 Jun 2023)) |
|
||||||
|
| |
|
||||||
|
+-----------------------+----------------------+------------------+
|
||||||
|
| cYEL |
|
||||||
|
| variants |
|
||||||
|
| (9, 5, 'XXL', [1 Mar 2022,1 Jun 2024)) |
|
||||||
|
| |
|
||||||
|
+-----------------------------------------+
|
||||||
|
|
||||||
|
| | | | | |
|
||||||
|
2020 2021 2022 2023 2024 ...
|
||||||
Reference in New Issue
Block a user