Truncate this column to `n` rows, discarding any rows beyond that point. Used by transaction rollback to restore the column to its pre-write state. Panics in debug builds if `n > self.len()`.
(&mut self, n: usize)
| 19 | /// Used by transaction rollback to restore the column to its pre-write state. |
| 20 | /// Panics in debug builds if `n > self.len()`. |
| 21 | pub(crate) fn truncate(&mut self, n: usize) { |
| 22 | debug_assert!( |
| 23 | n <= self.len(), |
| 24 | "truncate({n}) exceeds column length {}", |
| 25 | self.len() |
| 26 | ); |
| 27 | match self { |
| 28 | Self::Int64 { values, valid } => { |
| 29 | values.truncate(n); |
| 30 | if let Some(v) = valid { |
| 31 | v.truncate(n); |
| 32 | } |
| 33 | } |
| 34 | Self::Float64 { values, valid } => { |
| 35 | values.truncate(n); |
| 36 | if let Some(v) = valid { |
| 37 | v.truncate(n); |
| 38 | } |
| 39 | } |
| 40 | Self::Bool { values, valid } => { |
| 41 | values.truncate(n); |
| 42 | if let Some(v) = valid { |
| 43 | v.truncate(n); |
| 44 | } |
| 45 | } |
| 46 | Self::Timestamp { values, valid } => { |
| 47 | values.truncate(n); |
| 48 | if let Some(v) = valid { |
| 49 | v.truncate(n); |
| 50 | } |
| 51 | } |
| 52 | Self::Decimal { values, valid } => { |
| 53 | values.truncate(n); |
| 54 | if let Some(v) = valid { |
| 55 | v.truncate(n); |
| 56 | } |
| 57 | } |
| 58 | Self::Uuid { values, valid } => { |
| 59 | values.truncate(n); |
| 60 | if let Some(v) = valid { |
| 61 | v.truncate(n); |
| 62 | } |
| 63 | } |
| 64 | Self::String { |
| 65 | data, |
| 66 | offsets, |
| 67 | valid, |
| 68 | } => { |
| 69 | // offsets has length n_rows + 1; truncate to n+1. |
| 70 | if n < offsets.len().saturating_sub(1) { |
| 71 | let byte_end = offsets[n] as usize; |
| 72 | data.truncate(byte_end); |
| 73 | offsets.truncate(n + 1); |
| 74 | } |
| 75 | if let Some(v) = valid { |
| 76 | v.truncate(n); |
| 77 | } |
| 78 | } |