equal
deleted
inserted
replaced
117 |
117 |
118 List triggers:: |
118 List triggers:: |
119 |
119 |
120 \dy |
120 \dy |
121 |
121 |
122 |
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123 List misc info:: |
122 List misc info:: |
124 |
123 |
125 select current_database(); |
124 select current_database(); |
126 select current_schema(); |
125 select current_schema(); |
127 select current_user; |
126 select current_user; |
165 |
164 |
166 Largest table in the PostgreSQL database:: |
165 Largest table in the PostgreSQL database:: |
167 |
166 |
168 SELECT relname, relpages FROM pg_class ORDER BY relpages DESC; |
167 SELECT relname, relpages FROM pg_class ORDER BY relpages DESC; |
169 |
168 |
|
169 MVCC and transaction id |
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170 ======================= |
|
171 |
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172 As being MVCC Postgres doesn't delete or update existing rows. Row visibility is controled by |
|
173 transaction id (monotonous incremented number): ``xmin`` - first transaction that can see row, |
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174 ``xmax`` - last transaction that can see row::: |
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175 |
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176 SELECT xmin, xmax, * FROM foo WHERE id < 5 ORDER BY id; |
|
177 |
170 Using psql client |
178 Using psql client |
171 ================= |
179 ================= |
172 |
180 |
173 Using password file ``~/.pgpass``:: |
181 Using password file ``~/.pgpass``:: |
174 |
182 |